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␈↓ ↓H␈↓␈α?␈α?␈α
␈↓¬   BEINGS:␈↓

␈↓ ↓H␈↓␈α∀␈↓↓REPRESENTATION OF KNOWLEDGE
␈↓ ↓H␈↓↓␈α?␈α?␈α0AS INTERACTING MODULES


␈↓ ↓H␈↓␈α?␈α?␈α?␈α?␈α?␈α?␈α?␈α~␈↓βApplied to Automatic Program Synthesis␈↓











␈↓ ↓H␈↓Fourth Draft: NOT FOR DISTRIBUTION











␈↓ ↓H␈↓␈↓αDOUG LENAT

␈↓ ↓H␈↓αSTANFORD UNIVERSITY

␈↓ ↓H␈↓αARTIFICIAL INTELLIGENCE LABORATORY␈↓











␈↓ ↓H␈↓␈α?␈α?␈α?␈α?␈α?␈α?␈α?␈α?␈α?␈α?␈αα␈↓∧November 11, 1974␈↓␈↓ x














␈↓ ↓H␈↓␈↓↓TABLE OF CONTENTS␈↓










␈↓ ↓H␈↓    1.  Abstract  . . . . . . . . . . . . . . . .  1
␈↓ ↓H␈↓    2.  Introduction  . . . . . . . . . . . . . .  2
␈↓ ↓H␈↓    3.  Theory:   Ideas . . . . . . . . . . . . .  3
␈↓ ↓H␈↓    4.  Reality:  Examples  . . . . . . . . . . . 10
␈↓ ↓H␈↓    5.  Theory:   Design. . . . . . . . . . . . . 15
␈↓ ↓H␈↓    6.  Reality:  Examples  . . . . . . . . . . . 19
␈↓ ↓H␈↓    7.  Reality:  Results . . . . . . . . . . . . 23
␈↓ ↓H␈↓    8.  Theory:   Conclusions . . . . . . . . . . 28
␈↓ ↓H␈↓    9.  Acknowledgements  . . . . . . . . . . . . 32
␈↓ ↓H␈↓        Appendix 1: BEING parts . . . . . . . . . A1.1
␈↓ ↓H␈↓        Appendix 2: the BEINGs  . . . . . . . . . A2.1
␈↓ ↓H␈↓        Appendix 3: BEING usage . . . . . . . . . A3.1
␈↓ ↓H␈↓        Appendix 4: CF  program . . . . . . . . . A4.1
␈↓ ↓H␈↓        Appendix 5: the dialogue creating CF  . . A5.1
␈↓ ↓H␈↓        Appendix 6: trial running of CF . . . . . A6.1
␈↓ ↓H␈↓        Bibliography  . . . . . . . . . . . . . . BIB.1











␈↓ ↓H␈↓␈α?␈α?␈α?␈α?␈α?␈α?␈α?␈α?␈α?␈α?␈αα␈↓∧November 11, 1974␈↓␈↓ x
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓













␈↓ ↓H␈↓␈↓↓1. ABSTRACT␈↓











␈↓ ↓H␈↓Knowledge␈α∃may␈α∃be␈α∃organized␈α∃as␈α∀a␈α∃community␈α∃of␈α∃interacting␈α∃modules␈α∀(e.g.,
␈↓ ↓H␈↓ACTORS␈α∩[Hewitt]),␈α⊃in␈α∩which␈α∩control␈α⊃also␈α∩resides.␈α⊃ By␈α∩granting␈α∩each␈α⊃module
␈↓ ↓H␈↓a␈α⊂complex␈α⊂structure,␈α⊂yet␈α⊂constraining␈α⊂that␈α⊂that␈α⊂structure␈α⊂be␈α⊂standard␈α⊂over
␈↓ ↓H␈↓all␈α⊂the␈α⊂modules,␈α⊂some␈α⊂new␈α⊂theoretical␈α⊂and␈α⊂experimental␈α⊂results␈α⊂were␈α⊂found.
␈↓ ↓H␈↓The␈α⊂domain␈α⊂of␈α⊂this␈α⊂research␈α⊂was␈α⊂heuristic␈α⊂automatic␈α⊂synthesis␈α⊂of␈α⊂inductive
␈↓ ↓H␈↓inference␈α⊂LISP␈α⊂programs.␈α⊂ Since␈α⊂these␈α⊂modules,␈α⊂called␈α⊂BEINGs,␈α⊂are␈α⊂the␈α⊂only
␈↓ ↓H␈↓entities␈α⊂permitted␈α⊂to␈α⊂exist␈α⊂theoretically,␈α⊂the␈α⊂generated␈α⊂code␈α⊂must␈α⊂also␈α⊂be
␈↓ ↓H␈↓a␈α_community␈α_of␈α_BEINGs.␈α_ Like␈α_the␈α_original␈α_pool,␈α_the␈α_newly␈α_synthesized
␈↓ ↓H␈↓BEINGS␈α≤which␈α≥comprise␈α≤the␈α≥target␈α≤program␈α≥can␈α≤answer␈α≥questions␈α≤about
␈↓ ↓H␈↓themselves␈α⊂as␈α⊂they␈α⊂run.␈α⊂ An␈α⊂experimental␈α⊂system␈α⊂was␈α⊂partially␈α⊂implemented.
␈↓ ↓H␈↓It␈α≤synthesized␈α≥a␈α≤few␈α≥programs␈α≤from␈α≥very␈α≤restricted␈α≥dialogues.␈α≤ Some
␈↓ ↓H␈↓unexpected␈α"problems␈α"were␈α"encountered,␈α"and␈α"some␈α"aspects␈α"which␈α"were
␈↓ ↓H␈↓considered␈α⊗ignorable␈α⊗seem␈α⊗not␈α⊗to␈α∃be.␈α⊗ The␈α⊗performance␈α⊗of␈α⊗the␈α⊗system␈α∃is
␈↓ ↓H␈↓discussed, and a preliminary view of BEINGs assessed.












␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α≠page 1␈↓ 
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␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓␈↓↓2. INTRODUCTION␈↓

␈↓ ↓H␈↓This␈α≤paper␈α≥reports␈α≤on␈α≥a␈α≤scheme␈α≥(BEINGS)␈α≤for␈α≥representing␈α≤knowledge,
␈↓ ↓H␈↓partially␈α∃realized␈α⊗in␈α∃an␈α∃experimental␈α⊗system␈α∃(PUP6)␈α∃aimed␈α⊗at␈α∃generating
␈↓ ↓H␈↓LISP␈α∀programs␈α∃from␈α∀dialogues␈α∀with␈α∃the␈α∀user.␈α∀The␈α∃methods␈α∀employed␈α∃in␈α∀the
␈↓ ↓H␈↓programs'␈α→synthesis␈α→are␈α→not␈α→formal,␈α→but␈α→rather␈α→involve␈α→structuring␈α_of
␈↓ ↓H␈↓knowledge␈α∩about␈α⊃programming,␈α∩about␈α∩the␈α⊃task␈α∩domain,␈α⊃and␈α∩about␈α∩transfer␈α⊃of
␈↓ ↓H␈↓control.␈α~ To␈α~date,␈α~PUP6␈α~has␈α~synthesized␈α~three␈α~significantly␈α~different
␈↓ ↓H␈↓target␈α↔programs:␈α↔a␈α↔concept␈α↔formation␈α↔program␈α↔(similar␈α↔to␈α_[Winston]),␈α↔a
␈↓ ↓H␈↓grammatical␈α≡inference␈α≡program,␈α≡and␈α≡a␈α≡simple␈α≡information␈α≡storage␈α≡and
␈↓ ↓H␈↓retrieval␈α⊃on␈α∩keys␈α⊃system␈α∩(referred␈α⊃to␈α∩as,␈α⊃respectively,␈α∩CF,␈α⊃GI,␈α∩and␈α⊃INF).
␈↓ ↓H␈↓Specification␈α∪is␈α∪via␈α∪rigid,␈α∀extended␈α∪dialogues␈α∪carried␈α∪on␈α∪with␈α∀the␈α∪user,
␈↓ ↓H␈↓in␈α≤a␈α≤small␈α≤subset␈α≤of␈α≤English,␈α≤in␈α≤which␈α≤the␈α≤task␈α≤is␈α≤delineated␈α≤and
␈↓ ↓H␈↓questionable␈α⊂details␈α⊂are␈α⊂discussed.␈α⊂ The␈α⊂specification␈α⊂is␈α⊂partial,␈α⊂and␈α⊂the
␈↓ ↓H␈↓system␈α≠makes␈α≠assumptions␈α≠continually.␈α≤This␈α≠is␈α≠what␈α≠is␈α≠meant,␈α≤in␈α≠the
␈↓ ↓H␈↓sequel,␈α∀by␈α∃␈↓βAutomatic␈α∀Programming.␈α∃ Target␈α∀program␈↓␈α∀will␈α∃refer␈α∀to␈α∃code␈α∀which
␈↓ ↓H␈↓has␈α⊃been␈α∩successfully␈α⊃generated␈α∩by␈α⊃such␈α∩a␈α⊃system.␈α∩ This␈α⊃will␈α∩typically␈α⊃be
␈↓ ↓H␈↓written␈α≠in␈α≤the␈α≠same␈α≤language␈α≠as␈α≤the␈α≠system␈α≤itself.␈α≠ ␈↓βDialogue␈↓␈α≤is␈α≠the
␈↓ ↓H␈↓interactive␈α∀communication␈α∀between␈α∀the␈α∀user␈α∀and␈α∀the␈α∀automatic␈α∀programming
␈↓ ↓H␈↓system, which results in target code synthesis.

␈↓ ↓H␈↓Historically,␈α∩the␈α⊃CF␈α∩target␈α∩program␈α⊃was␈α∩first␈α⊃cleanly␈α∩specified.␈α∩Next,␈α⊃an
␈↓ ↓H␈↓annotated␈α≠protocol␈α≠was␈α≠done,␈α≤and␈α≠the␈α≠BEINGs␈α≠needed␈α≠to␈α≤reproduce␈α≠the
␈↓ ↓H␈↓reasoning␈α∪present␈α∪in␈α∪that␈α∀protocol␈α∪were␈α∪fasioned.␈α∪Additions␈α∪were␈α∀made␈α∪to
␈↓ ↓H␈↓PUP6 before it could synthesize GI or INF.

␈↓ ↓H␈↓The␈α⊂main␈α⊂successes␈α⊂of␈α⊂the␈α⊂experiment␈α⊂were␈α⊂that␈α⊂the␈α⊂desired␈α⊂reasoning␈α⊂steps
␈↓ ↓H␈↓in␈α⊃the␈α∩original␈α⊃protocol␈α∩were␈α⊃actually␈α∩simulated,␈α⊃most␈α∩of␈α⊃the␈α∩BEINGs␈α⊃were
␈↓ ↓H␈↓used␈α∀in␈α∀writing␈α∀more␈α∀than␈α∀one␈α∀of␈α∀the␈α∀programs,␈α∀and␈α∀the␈α∀synthesized␈α∀code
␈↓ ↓H␈↓could␈α⊂be␈α⊂interrupted␈α⊂and␈α⊂asked␈α⊂a␈α⊂few␈α⊂kinds␈α⊂of␈α⊂questions.␈α⊂ The␈α⊂main␈α⊂defects
␈↓ ↓H␈↓were␈α∪the␈α∪inflexibility␈α∪of␈α∪the␈α∪system␈α∪to␈α∪new␈α∪dialogues,␈α∪the␈α∪inability␈α∩for
␈↓ ↓H␈↓the␈α≤user␈α≥to␈α≤add␈α≥new,␈α≤high-level,␈α≥domain-specific␈α≤knowledge,␈α≥and␈α≤the
␈↓ ↓H␈↓verbosity␈α~of␈α~the␈α~system.␈α~ Some␈α≠of␈α~these␈α~problems␈α~may␈α~arise␈α≠from␈α~the
␈↓ ↓H␈↓annotated␈α⊂protocol␈α⊂technique␈α⊂employed␈α⊂to␈α⊂get␈α⊂the␈α⊂BEINGs␈α⊂initially,␈α⊂and␈α⊂not
␈↓ ↓H␈↓from anything inherent to the BEINGs representation.

␈↓ ↓H␈↓Our␈α⊗treatment␈α↔will␈α⊗follow␈α↔these␈α⊗lines:␈α⊗First,␈α↔the␈α⊗ideas␈α↔are␈α⊗presented,
␈↓ ↓H␈↓including␈α"a␈α"discussion␈α"of␈α!BEINGs.␈α" Examples␈α"are␈α"then␈α"provided␈α!to
␈↓ ↓H␈↓illustrate␈α∩these␈α∩concepts.␈α∩The␈α∩next␈α∩section␈α∩describes␈α∩the␈α∩implementation,
␈↓ ↓H␈↓and␈α≥explains␈α≥the␈α≥choice␈α≥of␈α≤targets.␈α≥ Only␈α≥then␈α≥will␈α≥performance␈α≤be
␈↓ ↓H␈↓evaluated.␈α∃ From␈α⊗the␈α∃experience␈α∃with␈α⊗PUP6␈α∃are␈α∃drawn␈α⊗several␈α∃preliminary
␈↓ ↓H␈↓conclusions␈α∩about␈α⊃both␈α∩the␈α∩utility␈α⊃of␈α∩the␈α⊃BEINGs␈α∩representation␈α∩and␈α⊃about
␈↓ ↓H␈↓problems relevant to Automatic Programming.

␈↓ ↓H␈↓The␈α~appendices␈α~present␈α~further␈α~details,␈α~samples,␈α~and␈α~examples.␈α~ First
␈↓ ↓H␈↓comes␈α∀a␈α∀description␈α∀of␈α∀each␈α∀BEING␈α∀part,␈α∀then␈α∀a␈α∀summary␈α∀of␈α∀the␈α∀knowledge
␈↓ ↓H␈↓contained␈α⊃in␈α⊃each␈α⊃BEING.␈α∩ Appendix␈α⊃3␈α⊃is␈α⊃a␈α∩table␈α⊃of␈α⊃data␈α⊃recording␈α∩how␈α⊃the


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α→page 2␈↓ 
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␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓BEING␈α∩community␈α∩interacts.␈α∩The␈α⊃final␈α∩appendices␈α∩present␈α∩excerpts␈α∩from␈α⊃the
␈↓ ↓H␈↓CF program, from PUP6 synthesizing CF, and from CF itself running.















































␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α→page 3␈↓ 
h
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓␈↓↓3. THEORY: IDEAS␈↓

␈↓ ↓H␈↓How␈α⊂should␈α⊂knowledge␈α⊂be␈α⊂represented?␈α⊂ Many␈α⊂researchers␈α⊂feel␈α⊂that␈α⊂a␈α⊂simple,
␈↓ ↓H␈↓uniform␈α∩formalism␈α⊃should␈α∩be␈α∩used␈α⊃for␈α∩all␈α⊃facts;␈α∩others␈α∩disagree,␈α⊃claiming
␈↓ ↓H␈↓that␈α≠complexity␈α≠of␈α~behavior␈α≠both␈α≠justifies␈α~and␈α≠demands␈α≠complexity␈α~of
␈↓ ↓H␈↓representation.␈α≡ The␈α≡BEINGs␈α≡concept␈α≡may␈α≡resolve␈α≡this␈α≡uniformity␈α≡vs.
␈↓ ↓H␈↓structure␈α≥controversy;␈α≥at␈α≥the␈α≥least,␈α≤it␈α≥is␈α≥a␈α≥compromise.␈α≥ One␈α≤must
␈↓ ↓H␈↓recognize␈α∃the␈α⊗advantages␈α∃of␈α∃each␈α⊗side,␈α∃and␈α∃refuse␈α⊗to␈α∃give␈α∃them␈α⊗up.␈α∃The
␈↓ ↓H␈↓benefits␈α⊗of␈α↔the␈α⊗former␈α↔include␈α⊗easy␈α⊗addition␈α↔of␈α⊗knowledge␈α↔[Newell]␈α⊗and
␈↓ ↓H␈↓simple,␈α⊂aesthetic␈α⊂methods␈α⊂for␈α⊂combining␈α⊂information␈α⊂[McCarthy].␈α⊂Structure,
␈↓ ↓H␈↓however,␈α≠is␈α≠necessary␈α≤for␈α≠(␈↓βcombinatorially␈↓)␈α≠efficient␈α≠handling␈α≤of␈α≠large
␈↓ ↓H␈↓amounts␈α∀of␈α∃data␈α∀(see␈α∀the␈α∃real␈α∀world;␈α∀also␈α∃[MIT]).␈α∀PUP6␈α∃integrates␈α∀these
␈↓ ↓H␈↓two␈α∃ideas␈α∃into␈α∃the␈α∃concept␈α∃of␈α∃BEINGs.␈α∃A␈α∃BEING␈α∃is␈α∃a␈α∃collection␈α∃of␈α∀about
␈↓ ↓H␈↓thirty␈α∃little␈α∃bits␈α∃of␈α∃INTERLISP␈α∀[Teitelman]␈α∃code;␈α∃the␈α∃answers␈α∃to␈α∀thirty
␈↓ ↓H␈↓questions␈α⊂about␈α⊂the␈α⊂BEING.␈α⊂ That␈α⊂is,␈α⊂a␈α⊂BEING␈α⊂is␈α⊂a␈α⊂small,␈α⊂loosely-knit␈α⊂LISP
␈↓ ↓H␈↓program,␈α_which␈α_is␈α_considered␈α_equivalent␈α_to␈α_its␈α_answers␈α_to␈α_these␈α_fixed
␈↓ ↓H␈↓questions.␈α∪ Every␈α∪scrap␈α∪of␈α∀knowledge␈α∪and␈α∪all␈α∪control␈α∪structure␈α∀should␈α∪be
␈↓ ↓H␈↓encoded␈α∪into␈α∪BEINGs.␈α∩There␈α∪should␈α∪be␈α∩nothing␈α∪else␈α∪in␈α∩the␈α∪system␈α∪but␈α∩this
␈↓ ↓H␈↓interacting community.

␈↓ ↓H␈↓PUP6␈α⊗embodies␈α⊗only␈α⊗some␈α⊗of␈α∃the␈α⊗ideas␈α⊗and␈α⊗constraints␈α⊗discussed␈α⊗in␈α∃this
␈↓ ↓H␈↓section.␈α" For␈α"example,␈α"economy␈α"demanded␈α"some␈α"very␈α"fast␈α"auxilliary
␈↓ ↓H␈↓functions,␈α&demons,␈α&and␈α&pure␈α&data␈α&structures.␈α& These␈α&reduced␈α&the
␈↓ ↓H␈↓computation␈α∀time␈α∃by␈α∀a␈α∀fixed␈α∃factor␈α∀(proportional␈α∀to␈α∃the␈α∀total␈α∃number␈α∀of
␈↓ ↓H␈↓BEINGs␈α≥in␈α≥the␈α≥system),␈α≥by␈α≥saving␈α≥on␈α≥the␈α≥overhead␈α≥implicit␈α≡in␈α≥each
␈↓ ↓H␈↓nondeterministic␈α≠call␈α≠to␈α≠a␈α≤BEING;␈α≠they␈α≠did␈α≠not␈α≠therefore␈α≤reduce␈α≠the
␈↓ ↓H␈↓␈↓βcombinatorial␈↓␈α∨effort␈α≡involved.␈α∨This␈α≡will␈α∨be␈α≡explained␈α∨in␈α∨the␈α≡REALITY
␈↓ ↓H␈↓section,␈α↔along␈α↔with␈α_any␈α↔other␈α↔deviations␈α↔of␈α_PUP6␈α↔from␈α↔an␈α_ideal␈α↔BEINGs
␈↓ ↓H␈↓community.

␈↓ ↓H␈↓Notice␈α~that␈α→while␈α~each␈α~BEING␈α→is␈α~highly␈α→structured,␈α~this␈α~structure␈α→is
␈↓ ↓H␈↓standard␈α∪over␈α∪the␈α∩entire␈α∪pool.␈α∪Each␈α∩BEING␈α∪part␈α∪is␈α∩itself␈α∪a␈α∪little␈α∩BEING,
␈↓ ↓H␈↓etc.,␈α∀and␈α∀this␈α∀infinite␈α∀regress␈α∀stops␈α∀when␈α∀the␈α∀contents␈α∀of␈α∀a␈α∀BEING␈α∀part
␈↓ ↓H␈↓becomes␈α↔sufficiently␈α↔primitive.␈α↔As␈α↔will␈α↔be␈α↔discussed␈α↔later,␈α_the␈α↔BEINGs
␈↓ ↓H␈↓mimic␈α⊂a␈α⊂human␈α⊂programmer;␈α⊂whatever␈α⊂he␈α⊂considers␈α⊂primitive␈α⊂when␈α⊂writing␈α⊂the
␈↓ ↓H␈↓program,␈α⊂BEINGs␈α⊂may␈α⊂consider␈α⊂primitive.␈α⊂ Typically␈α⊂this␈α⊂level␈α⊂is␈α⊂about␈α⊂the
␈↓ ↓H␈↓same␈α⊂as␈α⊂the␈α⊂INTERLISP␈α⊂language:␈α⊂a␈α⊂primitive␈α⊂is␈α⊂a␈α⊂single␈α⊂INTERLISP␈α⊂function
␈↓ ↓H␈↓call,␈α∪or␈α∪a␈α∪few␈α∪simple␈α∪ones␈α∪connected␈α∪trivially.␈α∪ Each␈α∪BEING␈α∪is␈α∩cognizant
␈↓ ↓H␈↓of␈α⊂the␈α⊂set␈α⊂of␈α⊂thirty␈α⊂questions,␈α⊂in␈α⊂the␈α⊂sense␈α⊂that␈α⊂in␈α⊂answering␈α⊂one␈α⊂of␈α⊂them
␈↓ ↓H␈↓it␈α,may␈α-freely␈α,ask␈α-questions␈α,of␈α-other␈α,BEINGs␈α-(often␈α,through
␈↓ ↓H␈↓nondeterministic␈α⊂goal␈α⊂statements.)␈α⊂A␈α⊂few␈α⊂of␈α⊂the␈α⊂BEING-PARTS␈α⊂might␈α⊂be:␈α⊂what
␈↓ ↓H␈↓is␈α∪your␈α∀basic␈α∪idea␈α∀and␈α∪purpose,␈α∀what␈α∪effects␈α∪do␈α∀you␈α∪have,␈α∀how␈α∪do␈α∀you␈α∪go
␈↓ ↓H␈↓about␈α⊂causing␈α⊂them,␈α⊂what␈α⊂must␈α⊂be␈α⊂ensured␈α⊂before␈α⊂you␈α⊂begin,␈α⊂how␈α⊂complicated
␈↓ ↓H␈↓are␈α↔you,␈α↔what␈α⊗is␈α↔your␈α↔chance␈α⊗of␈α↔success,␈α↔are␈α⊗you␈α↔recursive,␈α↔whom␈α⊗else
␈↓ ↓H␈↓might␈α⊂you␈α⊂transfer␈α⊂control␈α⊂to,␈α⊂what␈α⊂alternatives␈α⊂to␈α⊂you␈α⊂exist,␈α⊂what␈α⊂BEINGs
␈↓ ↓H␈↓are␈α≥a␈α≥little␈α≥more/less␈α≥general␈α≥than␈α≥you␈α≥are,␈α≥do␈α≥you␈α≡evaluate␈α≥your
␈↓ ↓H␈↓arguments,␈α∩what␈α∪is␈α∩the␈α∪nature␈α∩of␈α∪the␈α∩value␈α∪you␈α∩return,␈α∪why␈α∩do␈α∪you␈α∩exist,


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α→page 4␈↓ 	OTHEORY:  IDEAS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓why␈α∩do␈α∩you␈α∩want␈α∩to␈α∩be␈α∩in␈α∪control␈α∩now,␈α∩etc.␈α∩The␈α∩reader␈α∩may␈α∩wish␈α∪to␈α∩glance
␈↓ ↓H␈↓at␈α⊃Appendix␈α∩1,␈α⊃to␈α⊃see␈α∩the␈α⊃particular␈α⊃set␈α∩of␈α⊃questions␈α⊃which␈α∩were␈α⊃actually
␈↓ ↓H␈↓settled␈α∀upon.␈α∀ When␈α∀he␈α∀feels␈α∀the␈α∀urge␈α∀for␈α∀a␈α∀concrete␈α∀example,␈α∀he␈α∀should
␈↓ ↓H␈↓glance over pages 11-12 and Appendices 4 and 5.

␈↓ ↓H␈↓The␈α≥delineation␈α≡of␈α≥this␈α≥set␈α≡of␈α≥questions␈α≥has␈α≡much␈α≥to␈α≥do␈α≡with␈α≥the
␈↓ ↓H␈↓epistemology␈α∩of␈α∩programming.␈α∩ The␈α⊃BEING␈α∩parts␈α∩may␈α∩be␈α∩classified␈α⊃according
␈↓ ↓H␈↓to␈α↔their␈α↔usage.␈α↔ Each␈α↔BEING␈α↔part␈α↔has␈α↔two␈α↔tasks:␈α↔it␈α↔may␈α↔be␈α↔␈↓βasked␈↓␈α⊗about
␈↓ ↓H␈↓something,␈α_and␈α↔it␈α_may␈α_be␈α↔␈↓βcalled␈↓␈α_on␈α↔to␈α_do␈α_something.␈α↔Each␈α_of␈α_these␈α↔may
␈↓ ↓H␈↓involve␈α⊃asking␈α∩and␈α⊃calling␈α⊃other␈α∩parts␈α⊃of␈α⊃itself␈α∩and␈α⊃of␈α⊃other␈α∩BEINGs,␈α⊃but
␈↓ ↓H␈↓typically␈α∩the␈α⊃second␈α∩activity␈α∩involves␈α⊃an␈α∩extra␈α⊃level␈α∩of␈α∩evaluation.␈α⊃Some
␈↓ ↓H␈↓parts␈α_are␈α_relevant␈α_to␈α_only␈α_one␈α_of␈α_these␈α_functions;␈α_most␈α_are␈α_at␈α_least
␈↓ ↓H␈↓oriented␈α⊂more␈α⊂toward␈α⊂one␈α⊂than␈α⊂the␈α⊂other.␈α⊂For␈α⊂example,␈α⊂the␈α⊂ARGS␈α⊂part␈α⊂may␈α⊂be
␈↓ ↓H␈↓asked␈α⊗trivial␈α⊗questions␈α⊗about␈α⊗the␈α∃arguments␈α⊗to␈α⊗the␈α⊗BEING,␈α⊗but␈α⊗its␈α∃main
␈↓ ↓H␈↓role␈α⊂is␈α⊂to␈α⊂bind␈α⊂the␈α⊂arguments␈α⊂when␈α⊂the␈α⊂BEING␈α⊂is␈α⊂given␈α⊂control.␈α⊂In␈α⊂Appendix
␈↓ ↓H␈↓1,␈α⊃the␈α∩role␈α⊃of␈α⊃each␈α∩part␈α⊃is␈α⊃described.␈α∩The␈α⊃ask-oriented␈α⊃parts␈α∩divide␈α⊃into
␈↓ ↓H␈↓categories␈α∀based␈α∀on␈α∀why␈α∀they␈α∀are␈α∀queried:␈α∀to␈α∀decide␈α∀which␈α∀BEING␈α∀to␈α∀pass
␈↓ ↓H␈↓control,␈α∀to␈α∀tell␈α∪whether␈α∀the␈α∀BEING␈α∪has␈α∀a␈α∀certain␈α∪property,␈α∀or␈α∀to␈α∀give␈α∪a
␈↓ ↓H␈↓memorized␈α⊂English␈α⊂answer␈α⊂to␈α⊂the␈α⊂user␈α⊂under␈α⊂proper␈α⊂stimulation␈α⊂(examples␈α⊂of
␈↓ ↓H␈↓these three types are: WHEN, PREDICATE, WHAT).

␈↓ ↓H␈↓The␈α→BEINGs␈α→control␈α_themselves␈α→in␈α→a␈α→simple␈α_way.␈α→A␈α→very␈α→general␈α_BEING,
␈↓ ↓H␈↓SERVE_THE_USER,␈α∃has␈α∀control␈α∃initially.␈α∀In␈α∃general,␈α∀some␈α∃BEING␈α∀␈↓βB␈↓␈α∃will␈α∀be
␈↓ ↓H␈↓in␈α∃control.␈α∃ Its␈α∃BEING␈α∃parts␈α∀are␈α∃assembled␈α∃into␈α∃an␈α∃executable␈α∀function,
␈↓ ↓H␈↓and␈α∪it␈α∪is␈α∪run.␈α∀ During␈α∪the␈α∪course␈α∪of␈α∪its␈α∀reign,␈α∪␈↓βB␈↓␈α∪will␈α∪want␈α∀things␈α∪done
␈↓ ↓H␈↓and/or␈α⊃tested␈α∩which␈α⊃it␈α∩cannot␈α⊃manage␈α∩by␈α⊃itself.␈α∩ This␈α⊃corresponds␈α∩to␈α⊃when
␈↓ ↓H␈↓a␈α∪normal␈α∪program␈α∪needs␈α∀to␈α∪call␈α∪a␈α∪subroutine.␈α∪ What␈α∀␈↓βB␈↓␈α∪does␈α∪is␈α∪to␈α∀call␈α∪on
␈↓ ↓H␈↓SATISFY␈α~by␈α→name,␈α~supplying␈α~a␈α→description␈α~of␈α→what␈α~is␈α~wanted.␈α→ SATISFY
␈↓ ↓H␈↓assembles␈α⊂itself,␈α⊂asks␈α⊂the␈α⊂entire␈α⊂BEING␈α⊂pool␈α⊂"who␈α⊂can␈α⊂do␈α⊂this␈α⊂thing?",␈α⊂and
␈↓ ↓H␈↓collects␈α⊂a␈α⊂list␈α⊂of␈α⊂the␈α⊂reponders.␈α⊂ SATISFY␈α⊂then␈α⊂calls␈α⊂CHOOSE_FROM␈α⊂by␈α⊂name,
␈↓ ↓H␈↓supplying␈α⊃this␈α∩list␈α⊃and␈α∩the␈α⊃original␈α∩request.␈α⊃Each␈α∩responder␈α⊃is␈α∩asked␈α⊃why
␈↓ ↓H␈↓he␈α∩should␈α∩be␈α∩allowed␈α∩to␈α∩go␈α∩now␈α∪(the␈α∩WHEN␈α∩part)␈α∩and␈α∩how␈α∩costly␈α∩he␈α∪will␈α∩be
␈↓ ↓H␈↓if␈α↔he␈α↔does␈α⊗go␈α↔(the␈α↔COMPLEXITY␈α⊗part.)␈α↔The␈α↔best␈α⊗responder␈α↔BEING␈α↔is␈α⊗then
␈↓ ↓H␈↓passed␈α⊃control.␈α∩If␈α⊃he␈α∩succeeds␈α⊃in␈α∩his␈α⊃mission,␈α∩SATISFY␈α⊃returns␈α∩control␈α⊃to
␈↓ ↓H␈↓␈↓βB␈↓.␈α~Otherwise␈α~the␈α~remaining␈α~responders␈α~are␈α~compared␈α~and␈α~a␈α~new␈α~one␈α→is
␈↓ ↓H␈↓tried.␈α∩If␈α∩they␈α∩all␈α∩fail,␈α∩then␈α∩SATISFY␈α⊃tells␈α∩␈↓βB␈↓␈α∩that␈α∩it␈α∩has␈α∩failed.␈α∩␈↓βB␈↓␈α⊃then
␈↓ ↓H␈↓decides␈α∀whether␈α∀to␈α∀try␈α∀something␈α∀else␈α∀or␈α∀to␈α∀fail␈α∀itself.␈α∀In␈α∀addition␈α∀to
␈↓ ↓H␈↓these␈α⊂goal␈α⊂statements,␈α⊂there␈α⊂exists␈α⊂a␈α⊂"world"␈α⊂consisting␈α⊂of␈α⊂assertions␈α⊂and
␈↓ ↓H␈↓variables␈α_with␈α_values.␈α_These␈α_are␈α_regarded␈α_as␈α_trivial␈α_cases␈α_of␈α_BEINGs,
␈↓ ↓H␈↓possessing␈α∪only␈α∀one␈α∪part.␈α∀ So␈α∪␈↓βB␈↓␈α∀may␈α∪also␈α∀query␈α∪this␈α∀data␈α∪base␈α∀by␈α∪saying
␈↓ ↓H␈↓"what␈α→assertions␈α→match␈α_this␈α→one...",␈α→or␈α→by␈α_asking␈α→"what␈α→is␈α→the␈α_value
␈↓ ↓H␈↓of...".␈α∪ These␈α∪actions␈α∪can␈α∪be␈α∪programmed␈α∪in␈α∪a␈α∪much␈α∪more␈α∪efficient␈α∩manner
␈↓ ↓H␈↓than␈α∩as␈α∩BEINGs.␈α∩ Since␈α⊃they␈α∩never␈α∩employ␈α∩nondeterministic␈α∩transfers,␈α⊃they
␈↓ ↓H␈↓are␈α⊃faster␈α⊃by␈α⊃an␈α∩amount␈α⊃proportional␈α⊃to␈α⊃the␈α∩total␈α⊃number␈α⊃of␈α⊃BEINGs␈α∩in␈α⊃the
␈↓ ↓H␈↓system.

␈↓ ↓H␈↓The␈α∪CHOOSE_FROM␈α∪and␈α∪SATISFY␈α∀BEINGs␈α∪act␈α∪as␈α∪global␈α∪schedulers,␈α∀and␈α∪detract


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α→page 5␈↓ 	OTHEORY:  IDEAS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓from␈α⊂the␈α⊂equality␈α⊂proclaimed␈α⊂earlier␈α⊂for␈α⊂each␈α⊂BEING.␈α⊂This␈α⊂again␈α⊂touches␈α⊂on
␈↓ ↓H␈↓the␈α⊂philosophy␈α⊂of␈α⊂programming.␈α⊂Since␈α⊂the␈α⊂parts␈α⊂which␈α⊂reflect␈α⊂how␈α⊂desirable
␈↓ ↓H␈↓a␈α∩BEING␈α∪is␈α∩at␈α∪any␈α∩given␈α∪time␈α∩are␈α∪standard␈α∩over␈α∪all␈α∩BEINGs,␈α∪the␈α∩mechanism
␈↓ ↓H␈↓for␈α∀choosing␈α∀the␈α∀control␈α∀successor␈α∀will␈α∀be␈α∀about␈α∀the␈α∀same␈α∀whoever␈α∀is␈α∀in
␈↓ ↓H␈↓control.␈α→Either␈α→this␈α→choice␈α→algorithm␈α→must␈α→be␈α→duplicated␈α→inside␈α_every
␈↓ ↓H␈↓BEING,␈α⊂or␈α⊂else␈α⊂a␈α⊂universal␈α⊂chooser␈α⊂BEING␈α⊂must␈α⊂be␈α⊂tolerated.␈α⊂ It␈α⊂seems␈α⊂that
␈↓ ↓H␈↓one␈α→must␈α→have␈α_either␈α→duplication␈α→of␈α→knowledge␈α_or␈α→else␈α→factor␈α→out␈α_the
␈↓ ↓H␈↓common knowledge into some higher-level interaction BEINGs.

␈↓ ↓H␈↓Theory␈α≠would␈α≠indicate␈α≠that␈α≤BEINGs␈α≠must␈α≠be␈α≠assembled␈α≠by␈α≤other␈α≠BEINGs
␈↓ ↓H␈↓dynamically.␈α⊃In␈α∩practice,␈α⊃the␈α∩way␈α⊃a␈α∩BEING's␈α⊃parts␈α∩fit␈α⊃together␈α∩is␈α⊃uniform
␈↓ ↓H␈↓over␈α∪all␈α∪the␈α∩BEINGs␈α∪at␈α∪all␈α∩times.␈α∪Thus␈α∪one␈α∩simple␈α∪function␈α∪(or␈α∩assembled
␈↓ ↓H␈↓BEING)␈α⊗can␈α↔assemble␈α⊗all␈α↔the␈α⊗BEINGs␈α⊗initially␈α↔into␈α⊗LISP␈α↔functions.␈α⊗ The
␈↓ ↓H␈↓precise algorithm for doing this is discussed in section 4.2.

␈↓ ↓H␈↓BEINGs␈α⊗are␈α↔the␈α⊗only␈α↔entities␈α⊗permitted␈α⊗(theoretically)␈α↔to␈α⊗exist␈α↔in␈α⊗our
␈↓ ↓H␈↓system;␈α∩ergo␈α∪all␈α∩our␈α∪code␈α∩must␈α∪be␈α∩written␈α∪as␈α∩BEINGs,␈α∪and␈α∩must␈α∪be␈α∩written
␈↓ ↓H␈↓by BEINGs.

␈↓ ↓H␈↓An␈α∃obvious␈α∀but␈α∃crucial␈α∀consequence␈α∃is␈α∀that␈α∃␈↓βsome␈↓␈α∀BEING(s)␈α∃must␈α∃write␈α∀new
␈↓ ↓H␈↓BEINGs.␈α∀The␈α∪significant␈α∀point␈α∪is␈α∀that␈α∀the␈α∪BEING␈α∀who␈α∪knows␈α∀about␈α∀␈↓βX␈↓␈α∪takes
␈↓ ↓H␈↓charge␈α⊃of␈α⊃generating␈α⊃BEINGs␈α⊃relating␈α⊃to␈α⊃␈↓βX␈↓.␈α⊃ For␈α⊃example,␈α⊃the␈α⊃INSERT␈α⊃BEING
␈↓ ↓H␈↓can␈α∃do␈α∀inserting␈α∃by␈α∀one␈α∃of␈α∃a␈α∀few␈α∃algorithms,␈α∀and␈α∃he␈α∀can␈α∃also␈α∃write␈α∀(by
␈↓ ↓H␈↓specializing␈α↔himself)␈α↔more␈α↔specific␈α↔insert␈α↔routines,␈α↔and␈α↔he␈α_can␈α↔answer
␈↓ ↓H␈↓questions␈α⊗about␈α↔inserting.␈α⊗This␈α↔idea␈α⊗is␈α⊗analogous␈α↔to␈α⊗any␈α↔reliance␈α⊗upon
␈↓ ↓H␈↓experts␈α≠(e.g.,␈α≠[Feigenbaum]),␈α~and␈α≠also␈α≠reemphasizes␈α~the␈α≠theme␈α≠of␈α~any
␈↓ ↓H␈↓modular representation of knowledge.

␈↓ ↓H␈↓A␈α∃second␈α∃consequence␈α∃is␈α∃that␈α∃the␈α∀output␈α∃code␈α∃will␈α∃have␈α∃all␈α∃the␈α∃␈↓βtypes␈↓␈α∀of
␈↓ ↓H␈↓"intelligence"␈α∃that␈α∃any␈α∃BEING␈α∃community␈α∀has:␈α∃it␈α∃can␈α∃write␈α∃variations␈α∀of
␈↓ ↓H␈↓itself,␈α≠modify␈α≠itself␈α~according␈α≠to␈α≠the␈α~user's␈α≠complaints,␈α≠and␈α~answer
␈↓ ↓H␈↓questions␈α⊂about␈α⊂what␈α⊂it␈α⊂is␈α⊂doing␈α⊂as␈α⊂it␈α⊂runs.␈α⊂ The␈α⊂specialized␈α⊂code␈α⊂cannot,
␈↓ ↓H␈↓of␈α⊂course,␈α⊂write␈α⊂the␈α⊂full␈α⊂complement␈α⊂of␈α⊂programs␈α⊂the␈α⊂original␈α⊂system␈α⊂could
␈↓ ↓H␈↓write.

␈↓ ↓H␈↓In␈α⊗a␈α∃similar␈α⊗vein,␈α∃␈↓βsome␈↓␈α⊗BEING(s)␈α∃must␈α⊗do␈α∃the␈α⊗translation␈α∃of␈α⊗the␈α∃users'
␈↓ ↓H␈↓quasi-English␈α⊃inputs␈α⊃into␈α⊃BEING-usable␈α⊃form.␈α⊃␈↓&Each␈↓'β␈α⊃BEING␈α⊃␈↓βX␈↓␈α⊃is␈α∩charged␈α⊃with
␈↓ ↓H␈↓recognizing␈α∪English␈α∪related␈α∪to␈α∪␈↓βX␈↓.␈α∪ Thus␈α∪translation␈α∪consists␈α∪of␈α∪querying
␈↓ ↓H␈↓"who␈α→can␈α→recognize␈α_..."␈α→and␈α→waiting␈α→for␈α_a␈α→response.␈α→For␈α→example,␈α_our
␈↓ ↓H␈↓INSERT␈α∩BEING␈α∩must␈α∩also␈α⊃recognize␈α∩and␈α∩process␈α∩phrases␈α∩involving␈α⊃inserting,
␈↓ ↓H␈↓stack-pushing, and merging.

␈↓ ↓H␈↓A␈α↔result␈α↔of␈α_this␈α↔treatment␈α↔of␈α↔natural␈α_language␈α↔processing␈α↔is␈α_that␈α↔any
␈↓ ↓H␈↓phrase␈α∃which␈α⊗can␈α∃be␈α∃translated␈α⊗can␈α∃be␈α∃acted␈α⊗upon,␈α∃and␈α∃any␈α⊗phrase␈α∃which
␈↓ ↓H␈↓can't␈α⊂be␈α⊃translated␈α⊂probably␈α⊂␈↓βcan't␈↓␈α⊃be␈α⊂acted␈α⊂upon␈α⊃(even␈α⊂if␈α⊂it␈α⊃is␈α⊂rephrased).
␈↓ ↓H␈↓Since␈α~patterns␈α~are␈α~used,␈α~if␈α≠the␈α~global␈α~structure␈α~of␈α~the␈α≠sentence␈α~is
␈↓ ↓H␈↓recognized,␈α∃then␈α⊗the␈α∃user␈α∃need␈α⊗only␈α∃be␈α∃asked␈α⊗to␈α∃clear␈α∃up␈α⊗the␈α∃difficult
␈↓ ↓H␈↓sub-parts.

␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α→page 6␈↓ 	OTHEORY:  IDEAS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓A␈α↔few␈α↔constraints␈α_are␈α↔present␈α↔which␈α↔reflect␈α_new␈α↔biasses␈α↔more␈α_than␈α↔new
␈↓ ↓H␈↓insights:␈α"one␈α"need␈α"not␈α!feel␈α"any␈α"reverence␈α"toward␈α"the␈α!exploratory
␈↓ ↓H␈↓anthropomorphic␈α∩paradigm␈α∩of␈α∩programming␈α∩(ignore␈α∩details,␈α∩catch␈α∩them␈α∩later
␈↓ ↓H␈↓by␈α⊂debugging).␈α⊂ As␈α⊂in␈α⊂all␈α⊂programming,␈α⊂decisions␈α⊂continually␈α⊂crop␈α⊂up␈α⊂which
␈↓ ↓H␈↓the␈α∀system␈α∀is␈α∪not␈α∀able␈α∀to␈α∪resolve␈α∀at␈α∀the␈α∪time.␈α∀The␈α∀BEINGs␈α∀system␈α∪should
␈↓ ↓H␈↓always␈α≠spend␈α≠a␈α≠significant␈α≤effort␈α≠deferring␈α≠the␈α≠decision␈α≠as␈α≤long␈α≠as
␈↓ ↓H␈↓possible.␈α⊃ When,␈α∩at␈α⊃last,␈α∩no␈α⊃progress␈α∩can␈α⊃be␈α∩made␈α⊃without␈α∩its␈α⊃resolution,
␈↓ ↓H␈↓and␈α→if␈α~the␈α→system␈α→is␈α~still␈α→unsure,␈α→then␈α~either␈α→the␈α→user␈α~settles␈α→the
␈↓ ↓H␈↓question␈α⊗or␈α↔else␈α⊗a␈α↔backtrack␈α⊗point␈α⊗is␈α↔reluctantly␈α⊗set␈α↔up.␈α⊗ "Reluctant"
␈↓ ↓H␈↓means␈α∀that␈α∀it␈α∀is␈α∀the␈α∀last␈α∀of␈α∀several␈α∀alternatives␈α∀which␈α∀are␈α∀tried.␈α∀ But
␈↓ ↓H␈↓often,␈α⊗by␈α⊗this␈α⊗time,␈α⊗some␈α∃new␈α⊗information␈α⊗is␈α⊗present␈α⊗which␈α⊗enables␈α∃the
␈↓ ↓H␈↓system␈α∩to␈α⊃resolve␈α∩the␈α∩decision,␈α⊃thus␈α∩reducing␈α⊃the␈α∩amount␈α∩of␈α⊃backtracking.
␈↓ ↓H␈↓If␈α∀there␈α∀are␈α∪two␈α∀or␈α∀more␈α∪decisions␈α∀which␈α∀can␈α∪no␈α∀longer␈α∀be␈α∀deferred,␈α∪the
␈↓ ↓H␈↓system␈α⊗tackles␈α⊗first␈α⊗the␈α⊗one␈α∃estimated␈α⊗to␈α⊗be␈α⊗the␈α⊗easiest␈α⊗(analogous␈α∃to
␈↓ ↓H␈↓Occam's razor).

␈↓ ↓H␈↓The␈α∨final␈α≡prejudice␈α∨is␈α≡that␈α∨most␈α≡of␈α∨the␈α≡carelessness␈α∨bugs␈α∨can␈α≡be
␈↓ ↓H␈↓eliminated␈α∀through␈α∀this␈α∀deferral,␈α∀feed-forward,␈α∀and␈α∀very␈α∀precise␈α∀record-
␈↓ ↓H␈↓keeping.␈α& Humans␈α&depend␈α&on␈α&their␈α&adaptability␈α&to␈α&compensate␈α&for
␈↓ ↓H␈↓limitations␈α⊂in␈α⊂their␈α⊂brain␈α⊂hardware␈α⊂(long␈α⊂write␈α⊂times␈α⊂for␈α⊂long-term␈α⊂memory
␈↓ ↓H␈↓and␈α⊂external␈α⊂memory,␈α⊂and␈α⊂limited␈α⊂short-term␈α⊂memory␈α⊂size␈α⊂force␈α⊂us␈α⊂to␈α⊂ignore
␈↓ ↓H␈↓details;␈α∃see␈α∀[Newell])␈α∃but␈α∀there␈α∃is␈α∀no␈α∃need␈α∀for␈α∃an␈α∃␈↓βautomatic␈↓␈α∀programming
␈↓ ↓H␈↓system␈α⊂to␈α⊂do␈α⊂so.␈α⊂ For␈α⊂example,␈α⊂when␈α⊂a␈α⊂list␈α⊂structure␈α⊂is␈α⊂first␈α⊂encountered,
␈↓ ↓H␈↓the␈α⊂system␈α⊂records␈α⊂warnings␈α⊂that␈α⊂it␈α⊂is␈α⊂undefined,␈α⊂no␈α⊂accesses,␈α⊂insertions,
␈↓ ↓H␈↓or␈α⊃deletions␈α∩have␈α⊃been␈α⊃observed,␈α∩and␈α⊃so␈α⊃on.␈α∩ Each␈α⊃such␈α⊃worry␈α∩is␈α⊃weighted,
␈↓ ↓H␈↓and␈α⊂periodically␈α⊂the␈α⊂system␈α⊂resolves␈α⊂such␈α⊂warning␈α⊂notes␈α⊂--␈α⊂especially␈α⊂near
␈↓ ↓H␈↓the completion of the target program.

␈↓ ↓H␈↓To␈α⊃understand␈α∩why␈α⊃Automatic␈α⊃Programming␈α∩is␈α⊃a␈α⊃good␈α∩task␈α⊃for␈α⊃a␈α∩BEINGs␈α⊃pool,
␈↓ ↓H␈↓it␈α"is␈α"necessary␈α"to␈α!defocus␈α"our␈α"interest␈α"momentarily.␈α" The␈α!BEINGs
␈↓ ↓H␈↓representation␈α"may␈α!be␈α"suitable␈α!for␈α"simulating␈α!any␈α"complex␈α"task␈α!␈↓βT␈↓
␈↓ ↓H␈↓involving␈α∩frequent␈α∩small␈α∩interventions␈α⊃by␈α∩various␈α∩experts.␈α∩In␈α∩addition␈α⊃to
␈↓ ↓H␈↓writing␈α⊗programs,␈α↔this␈α⊗activity␈α↔could␈α⊗perhaps␈α⊗be␈α↔as␈α⊗diverse␈α↔as␈α⊗playing
␈↓ ↓H␈↓chess,␈α∀running␈α∀a␈α∀business,␈α∀simulating␈α∀physical␈α∀interactions,␈α∀and␈α∀playing
␈↓ ↓H␈↓volleyball.␈α⊗ For␈α↔the␈α⊗latter␈α↔task,␈α⊗a␈α⊗BEINGs-based␈α↔system␈α⊗might␈α↔create␈α⊗a
␈↓ ↓H␈↓specialized␈α≤BEING␈α≥for␈α≤each␈α≥player,␈α≤perhaps␈α≥with␈α≤a␈α≥complexity␈α≤vector
␈↓ ↓H␈↓indicating␈α∃his␈α∃abilities,␈α∃reflexes,␈α∃etc.␈α∀ The␈α∃BEING␈α∃in␈α∃control␈α∃would␈α∀be
␈↓ ↓H␈↓the␈α∩player␈α⊃hitting␈α∩the␈α∩ball.␈α⊃A␈α∩specialized␈α⊃Choose-from␈α∩BEING␈α∩would␈α⊃decide
␈↓ ↓H␈↓who␈α∃goes␈α∃next,␈α∃occasionally␈α∃interpreting␈α∀a␈α∃tie␈α∃between␈α∃BEINGs␈α∃vying␈α∀for
␈↓ ↓H␈↓control as a collision on the court.

␈↓ ↓H␈↓There␈α⊂is␈α⊂one␈α⊂particular␈α⊂bias␈α⊂of␈α⊂BEINGs␈α⊂toward␈α⊂writing␈α⊂high-level␈α⊂programs,
␈↓ ↓H␈↓over␈α∀other␈α∃activities.␈α∀The␈α∀new␈α∃BEINGs␈α∀created␈α∀during␈α∃the␈α∀execution␈α∃of␈α∀a
␈↓ ↓H␈↓specified␈α⊃task␈α∩are␈α⊃kept␈α⊃distinct␈α∩from␈α⊃the␈α⊃original␈α∩set␈α⊃of␈α⊃BEINGs.␈α∩ Then␈α⊃a
␈↓ ↓H␈↓␈↓βprogram␈↓␈α∃for␈α∃task␈α∃␈↓βT␈↓␈α∃is␈α∃accomplished␈α∃by␈α∃doing␈α∃␈↓βT␈↓␈α∃and␈α∃then␈α∃dumping␈α∃the␈α∀new
␈↓ ↓H␈↓BEINGs␈α⊂out␈α⊂onto␈α⊂a␈α⊂new␈α⊂file.␈α⊂ The␈α⊂entire␈α⊂old␈α⊂BEINGs␈α⊂pool␈α⊂is␈α⊂then␈α⊂treated␈α⊂as
␈↓ ↓H␈↓the␈α∪language␈α∪supporting␈α∪this␈α∀file.␈α∪As␈α∪a␈α∪corollary,␈α∪asking␈α∀a␈α∪BEINGs-based
␈↓ ↓H␈↓system to write any subset of itself is the null task.

␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α→page 7␈↓ 	OTHEORY:  IDEAS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓Most␈α programmers␈α intentionally␈α augment␈α their␈α code␈α to␈α aid␈α in␈α later
␈↓ ↓H␈↓debugging,␈α≡modification,␈α≡and␈α≡readability␈α≡by␈α≡humans.␈α≡ These␈α≡aids␈α≡are
␈↓ ↓H␈↓typically␈α comments,␈α summaries,␈α over-generalized␈α subroutines,␈α optional
␈↓ ↓H␈↓print␈α∩statements,␈α∩and␈α∩runtime␈α⊃statistics.␈α∩ Recently,␈α∩the␈α∩structure␈α∩of␈α⊃the
␈↓ ↓H␈↓program␈α⊂itself␈α⊂has␈α⊂also␈α⊂been␈α⊂recognized␈α⊂as␈α⊂a␈α⊂powerful␈α⊂manipulable␈α⊂element,
␈↓ ↓H␈↓affecting␈α∀the␈α∃accessability␈α∀of␈α∀the␈α∃code,␈α∀not␈α∀just␈α∃its␈α∀length␈α∃or␈α∀running
␈↓ ↓H␈↓time.␈α∀ The␈α∀length␈α∪of␈α∀any␈α∀program␈α∪written␈α∀as␈α∀a␈α∪pool␈α∀of␈α∀BEINGs␈α∀is␈α∪several
␈↓ ↓H␈↓times␈α∪as␈α∪long␈α∩as␈α∪a␈α∪clean␈α∩hand-coded␈α∪version.␈α∪ This␈α∩extra␈α∪code,␈α∪the␈α∩parts
␈↓ ↓H␈↓of␈α∪each␈α∪new␈α∪BEING␈α∪which␈α∪are␈α∪superfluous,␈α∪may␈α∪be␈α∪viewed␈α∪as␈α∩well-organized
␈↓ ↓H␈↓self-documentation.␈α→ They␈α→should␈α→improve␈α→the␈α→debugging,␈α~expansion,␈α→and
␈↓ ↓H␈↓accessibility (to alien users) of the synthesized code.

␈↓ ↓H␈↓Some␈α⊃assertions␈α∩are␈α⊃so␈α⊃meaningful␈α∩to␈α⊃the␈α⊃user,␈α∩that␈α⊃they␈α⊃should␈α∩be␈α⊃stored
␈↓ ↓H␈↓in␈α∃the␈α∃code␈α∃itself,␈α∃even␈α∃if␈α∃they␈α∃are␈α∃only␈α∃temporary.␈α∃ At␈α∃any␈α∃time,␈α∀the
␈↓ ↓H␈↓user␈α→may␈α~look␈α→at␈α~a␈α→piece␈α~of␈α→code;␈α~the␈α→comments␈α~present␈α→␈↓βthen␈↓␈α~are␈α→all
␈↓ ↓H␈↓assertions␈α⊃pertaining␈α∩to␈α⊃that␈α⊃piece␈α∩of␈α⊃code␈α⊃at␈α∩that␈α⊃time.␈α⊃ BEINGS␈α∩may␈α⊃use
␈↓ ↓H␈↓comments␈α∪at␈α∪several␈α∪different␈α∀levels.␈α∪ At␈α∪the␈α∪lowest␈α∪level,␈α∀each␈α∪comment
␈↓ ↓H␈↓is␈α∀merely␈α∀a␈α∀unique␈α∀token;␈α∀it␈α∀may␈α∀be␈α∀inserted,␈α∀removed,␈α∀or␈α∀searched␈α∀for.
␈↓ ↓H␈↓Slightly␈α∪better,␈α∪the␈α∪BEINGs␈α∪system␈α∪can␈α∪ask␈α∪"is␈α∪there␈α∪a␈α∪comment␈α∩involving
␈↓ ↓H␈↓...".␈α∀For␈α∃this␈α∀purpose,␈α∀a␈α∃constrained␈α∀syntax␈α∀for␈α∃the␈α∀comments␈α∃should␈α∀be
␈↓ ↓H␈↓developed.␈α∩Otherwise␈α⊃(as,␈α∩unfortunately␈α∩in␈α⊃PUP6)␈α∩each␈α⊃new␈α∩comment␈α∩must␈α⊃be
␈↓ ↓H␈↓attended␈α⊂to␈α⊂ad␈α⊂hoc.␈α⊂ Still␈α⊂higher␈α⊂level␈α⊂usage␈α⊂of␈α⊂comments␈α⊂would␈α⊂occur␈α⊂if␈α⊂a
␈↓ ↓H␈↓BEING␈α∪looked␈α∪at␈α∩a␈α∪comment␈α∪totally␈α∩ignorant␈α∪of␈α∪it,␈α∩and␈α∪TRANSLATEd␈α∪it␈α∩into
␈↓ ↓H␈↓something meaningful.

␈↓ ↓H␈↓When␈α∩imagining␈α⊃an␈α∩ideal␈α∩AP␈α⊃(automatic␈α∩programming)␈α⊃system,␈α∩one␈α∩ability␈α⊃we
␈↓ ↓H␈↓might␈α↔wish␈α↔for␈α⊗is␈α↔that␈α↔it␈α⊗be␈α↔able␈α↔to␈α⊗input␈α↔a␈α↔well-documented␈α⊗program,
␈↓ ↓H␈↓glean␈α⊂pure␈α⊂programming␈α⊂knowledge␈α⊂from␈α⊂it,␈α⊂and␈α⊂transform␈α⊂this␈α⊂into␈α⊂a␈α⊂format
␈↓ ↓H␈↓it␈α⊃can␈α⊃use.␈α⊃ Also,␈α∩to␈α⊃improve␈α⊃itself,␈α⊃it␈α∩should␈α⊃be␈α⊃capable␈α⊃of␈α∩digesting␈α⊃a
␈↓ ↓H␈↓sample,␈α⊂valid␈α⊂AP␈α⊂dialog,␈α⊂and␈α⊂(perhaps␈α⊂through␈α⊂additional␈α⊂user␈α⊂interaction)
␈↓ ↓H␈↓modify␈α⊂itself␈α⊂so␈α⊂it␈α⊂could␈α⊂actually␈α⊂carry␈α⊂on␈α⊂that␈α⊂dialog.␈α⊂ Another␈α⊂ideal␈α⊂to
␈↓ ↓H␈↓hope␈α∩for␈α∩is␈α∪that␈α∩the␈α∩user␈α∪be␈α∩permitted␈α∩to␈α∩do␈α∪whatever␈α∩he␈α∩can␈α∪whenever␈α∩he
␈↓ ↓H␈↓can;␈α⊂if␈α⊂he␈α⊂suddenly␈α⊂thinks␈α⊂of␈α⊂a␈α⊂stray␈α⊂caution,␈α⊂the␈α⊂AP␈α⊂system␈α⊂should␈α⊂accept
␈↓ ↓H␈↓it␈α⊃(e.g.,␈α⊃"Oh,␈α⊃I␈α∩might␈α⊃want␈α⊃to␈α⊃type␈α∩in␈α⊃HALT␈α⊃instead␈α⊃of␈α∩STOP,␈α⊃sometimes").
␈↓ ↓H␈↓BEINGs␈α∩were␈α∪not␈α∩designed␈α∪with␈α∩these␈α∪ideals␈α∩in␈α∪mind,␈α∩and␈α∪as␈α∩a␈α∪result␈α∩they
␈↓ ↓H␈↓may␈α_be␈α_an␈α_insufficient␈α_framework␈α_for␈α_achieving␈α_this.␈α_ By␈α_studying␈α_the
␈↓ ↓H␈↓difficulties␈α∃of␈α⊗the␈α∃implementation␈α∃of␈α⊗the␈α∃BEINGs␈α∃ideas,␈α⊗isolating␈α∃those
␈↓ ↓H␈↓due␈α→to␈α~poor␈α→programming␈α→from␈α~those␈α→due␈α→to␈α~poor␈α→ideas,␈α→enough␈α~may␈α→be
␈↓ ↓H␈↓learned␈α→to␈α→build␈α_the␈α→next␈α→system␈α→one␈α_qualitative␈α→step␈α→closer␈α→to␈α_this
␈↓ ↓H␈↓ideal.

␈↓ ↓H␈↓It␈α∪is␈α∪in␈α∩this␈α∪spirit␈α∪that␈α∩BEINGs␈α∪are␈α∪now␈α∩contrasted␈α∪against␈α∪the␈α∩concepts
␈↓ ↓H␈↓of␈α⊂ACTORs,␈α⊂CLASSes,␈α⊂FRAMES,␈α⊂HACKER,␈α⊂formal␈α⊂AP␈α⊂systems,␈α⊂and␈α⊂macro␈α⊂expansion
␈↓ ↓H␈↓schemes.

␈↓ ↓H␈↓ACTORS␈α→[Hewitt]␈α→provided␈α→the␈α→key␈α→concept␈α→of␈α→integrating␈α→uniformity␈α_of
␈↓ ↓H␈↓construction␈α∩with␈α∩sophistocation␈α∩of␈α⊃behavior.␈α∩There␈α∩is␈α∩a␈α∩continuum,␈α⊃among


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α→page 8␈↓ 	OTHEORY:  IDEAS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓modular␈α∀knowledge␈α∀schemes,␈α∀of␈α∀standardization␈α∀of␈α∀"message"␈α∀types␈α∀between
␈↓ ↓H␈↓modules.␈α⊂ACTORs␈α⊂have␈α⊂no␈α⊂restriction␈α⊂whatsoever␈α⊂on␈α⊂this␈α⊂format.␈α⊂Each␈α⊂module
␈↓ ↓H␈↓has␈α⊃its␈α⊃own,␈α⊃unique␈α∩parts␈α⊃(types␈α⊃of␈α⊃answers).␈α∩So␈α⊃each␈α⊃ACTOR␈α⊃must␈α∩be␈α⊃aware
␈↓ ↓H␈↓of␈α∩all␈α∩the␈α∪parts␈α∩(message␈α∩formats)␈α∪of␈α∩all␈α∩the␈α∩ACTORs␈α∪it␈α∩ever␈α∩is␈α∪going␈α∩to
␈↓ ↓H␈↓communicate␈α∃with.␈α∃Adding␈α∃a␈α∃new␈α∀module␈α∃is␈α∃thus␈α∃conceptually␈α∃intricate␈α∀as
␈↓ ↓H␈↓well␈α∃as␈α⊗practically␈α∃difficult.␈α∃CLASSes␈α⊗[..........]␈α∃have␈α∃a␈α⊗few␈α∃standard
␈↓ ↓H␈↓parts,␈α∩and␈α∪the␈α∩modules␈α∪are␈α∩arranged␈α∪in␈α∩groups,␈α∪each␈α∩of␈α∪which␈α∩has␈α∪its␈α∩own
␈↓ ↓H␈↓additional␈α⊂types␈α⊂of␈α⊂parts.␈α⊃Thus␈α⊂a␈α⊂module␈α⊂can␈α⊂ask␈α⊃␈↓βany␈↓␈α⊂other␈α⊂module␈α⊂one␈α⊃of␈α⊂a
␈↓ ↓H␈↓few␈α≠universal␈α≠questions,␈α~and␈α≠it␈α≠can␈α~ask␈α≠any␈α≠module␈α~in␈α≠its␈α≠group␈α~an
␈↓ ↓H␈↓additional␈α~set␈α~of␈α~questions.␈α~If␈α≠it␈α~is␈α~permitted␈α~to␈α~know␈α≠about␈α~other
␈↓ ↓H␈↓groups'␈α→special␈α→parts,␈α_then␈α→the␈α→same␈α→adding␈α_problem␈α→recurs.␈α→If␈α→it␈α_is
␈↓ ↓H␈↓denied␈α⊂such␈α⊂knowledge,␈α⊂it␈α⊂cannot␈α⊂access␈α⊂much␈α⊂of␈α⊂the␈α⊂knowledge␈α⊂in␈α⊂the␈α⊂pool.
␈↓ ↓H␈↓If␈α⊃one␈α∩requires␈α⊃a␈α⊃completely␈α∩universal␈α⊃set␈α⊃of␈α∩message␈α⊃types,␈α⊃then␈α∩most␈α⊃of
␈↓ ↓H␈↓them␈α∀will␈α∀be␈α∀irrelevant␈α∀to␈α∀most␈α∀modules.␈α∀This␈α∀is␈α∀the␈α∀price␈α∀which␈α∀BEINGs
␈↓ ↓H␈↓pay.␈α≤Later,␈α≤it␈α≤will␈α≤be␈α≤shown␈α≤that␈α≤this␈α≤superfluity␈α≤is␈α≤real␈α≤and␈α≤is
␈↓ ↓H␈↓marginally␈α↔tolerable.␈α↔The␈α↔most␈α↔devastating␈α↔criticism␈α↔of␈α↔striving␈α_for␈α↔a
␈↓ ↓H␈↓universal␈α∀set␈α∀of␈α∪module␈α∀questions␈α∀is␈α∪that␈α∀all␈α∀this␈α∪does␈α∀is␈α∀push␈α∀all␈α∪the
␈↓ ↓H␈↓non-uniformity␈α⊗down␈α⊗into␈α⊗the␈α⊗values␈α∃of␈α⊗these␈α⊗parts.␈α⊗The␈α⊗only␈α⊗retort␈α∃is
␈↓ ↓H␈↓empirical:␈α⊃if␈α∩a␈α⊃good␈α⊃partitioning␈α∩of␈α⊃the␈α⊃questions␈α∩can␈α⊃be␈α⊃found,␈α∩then␈α⊃the
␈↓ ↓H␈↓internal␈α⊂structure␈α⊂of␈α⊂each␈α⊂part␈α⊂with␈α⊂the␈α⊂same␈α⊂name␈α⊂will␈α⊂be␈α⊂comparable,␈α⊂and
␈↓ ↓H␈↓the␈α∀only␈α∪communication␈α∀necessary␈α∪will␈α∀be␈α∪simple␈α∀questioning␈α∀of␈α∪modules's
␈↓ ↓H␈↓parts.

␈↓ ↓H␈↓FRAMES␈α [Minsky]␈α seems␈α superficially␈α similar␈α to␈α BEINGs,␈α and␈α are␈α so
␈↓ ↓H␈↓amorphous␈α≥that␈α≥they␈α≥actually␈α≥could␈α≤subsume␈α≥BEINGs.␈α≥There␈α≥is␈α≥a␈α≤deep
␈↓ ↓H␈↓difference␈α$of␈α$philosophy␈α$and␈α$of␈α$intended␈α$usage,␈α$however.␈α$ FRAMES
␈↓ ↓H␈↓intentionally␈α∀have␈α∪default␈α∀values␈α∪already␈α∀(with␈α∪no␈α∀processing)␈α∀filled␈α∪in
␈↓ ↓H␈↓for␈α≤each␈α≠frame,␈α≤and␈α≤replaced␈α≠only␈α≤when␈α≤necessary.␈α≠ This␈α≤is␈α≤akin␈α≠to
␈↓ ↓H␈↓automatic␈α≠programming␈α≠by␈α~blind␈α≠debugging,␈α≠but␈α~is␈α≠antithetical␈α≠to␈α~the
␈↓ ↓H␈↓fastidious␈α_bookkeeping␈α_BEINGs␈α_philosophy.␈α_ As␈α_an␈α_example,␈α_consider␈α_the
␈↓ ↓H␈↓writing␈α∃of␈α⊗a␈α∃short,␈α∃recursive,␈α⊗list␈α∃manipulation␈α∃LISP␈α⊗program␈α∃(reverse,
␈↓ ↓H␈↓flatten,␈α∪assoc,␈α∪alternate,␈α∪etc.)␈α∀A␈α∪human,␈α∪consulting␈α∪the␈α∪proper␈α∀frame␈α∪in
␈↓ ↓H␈↓his␈α⊗head,␈α⊗knows␈α∃to␈α⊗ignore␈α⊗the␈α⊗base␈α∃step␈α⊗for␈α⊗a␈α∃while,␈α⊗then␈α⊗fill␈α⊗it␈α∃in,
␈↓ ↓H␈↓usually␈α⊃as␈α⊃␈↓βif␈α⊂NIL,␈α⊃then␈α⊃NIL␈↓.␈α⊂ The␈α⊃human␈α⊃makes␈α⊂this␈α⊃default␈α⊃synthesis,␈α⊂tries
␈↓ ↓H␈↓out␈α∪the␈α∪program,␈α∩and␈α∪looks␈α∪closer␈α∩(to␈α∪fill␈α∪in␈α∩this␈α∪"slot"␈α∪properly)␈α∩only
␈↓ ↓H␈↓if␈α⊂something␈α⊂calls␈α⊂his␈α⊂attention␈α⊂to␈α⊂it␈α⊂(such␈α⊂as␈α⊂a␈α⊂LISP␈α⊂error␈α⊂message:␈α⊂NON-
␈↓ ↓H␈↓NUMERIC␈α⊃ARG␈α⊃␈↓βNIL␈↓,␈α⊃e.g.,␈α⊃if␈α⊃what␈α⊃was␈α⊃really␈α⊃needed␈α⊃was␈α⊃the␈α⊃base␈α⊃step␈α⊃␈↓βif␈α⊂NIL,
␈↓ ↓H␈↓βthen␈α∪0␈↓).␈α∀ A␈α∪BEINGs␈α∀system␈α∪would␈α∀also␈α∪defer␈α∀working␈α∪on␈α∀the␈α∪base␈α∀step,␈α∪but
␈↓ ↓H␈↓could␈α∨--␈α∨and␈α≡would␈α∨--␈α∨place␈α≡a␈α∨note␈α∨about␈α≡that␈α∨deferral␈α∨into␈α≡the
␈↓ ↓H␈↓assertional␈α↔warning␈α↔base.␈α↔ Before␈α↔thinking␈α↔it␈α↔was␈α↔finished,␈α_the␈α↔system
␈↓ ↓H␈↓would␈α∀attend␈α∀to␈α∀that␈α∀note␈α∀carefully.␈α∀This␈α∀is␈α∀not␈α∀a␈α∀criticism␈α∀of␈α∀FRAMES:
␈↓ ↓H␈↓they␈α∀are␈α∀meant␈α∀to␈α∀be␈α∀a␈α∀construct␈α∀to␈α∀model␈α∀perception,␈α∀and␈α∀therefore␈α∀the
␈↓ ↓H␈↓default␈α'concept␈α'makes␈α'sense␈α'for␈α'them.␈α'BEINGs␈α'are␈α(clearly␈α'non-
␈↓ ↓H␈↓anthropomorphic␈α→in␈α→their␈α→internal␈α→workings,␈α→and␈α→would␈α→be␈α→very␈α_awkward
␈↓ ↓H␈↓models of human perceptual mechanisms.

␈↓ ↓H␈↓HACKER␈α⊂[Sussman]␈α⊂differs␈α⊂from␈α⊂BEINGs␈α⊂in␈α⊂the␈α⊂same␈α⊂qualitative␈α⊂way␈α⊂as␈α⊂FRAMES


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α→page 9␈↓ 	OTHEORY:  IDEAS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓do.␈α⊃ The␈α∩orientation␈α⊃of␈α⊃HACKER␈α∩is␈α⊃to␈α⊃put␈α∩together␈α⊃pieces␈α⊃of␈α∩programs␈α⊃into
␈↓ ↓H␈↓something␈α∀close␈α∀to␈α∀the␈α∀final␈α∀desired␈α∀target,␈α∀then␈α∀try␈α∀and␈α∀run␈α∀it.␈α∀ When
␈↓ ↓H␈↓errors␈α⊗result,␈α↔they␈α⊗are␈α↔analyzed␈α⊗and␈α⊗then␈α↔patched.␈α⊗ BEINGs␈α↔is␈α⊗oriented
␈↓ ↓H␈↓toward␈α⊂writing␈α⊂bug-free␈α⊂code;␈α⊂what␈α⊂it␈α⊂writes␈α⊂must␈α⊂always␈α⊂coincide␈α⊂with␈α⊂its
␈↓ ↓H␈↓internal␈α⊃specifications␈α∩of␈α⊃that␈α∩code.␈α⊃The␈α∩user␈α⊃may␈α∩later␈α⊃change␈α∩his␈α⊃mind,
␈↓ ↓H␈↓and␈α⊗a␈α⊗BEINGs␈α⊗system␈α⊗must␈α⊗be␈α↔able␈α⊗to␈α⊗modify␈α⊗its␈α⊗own␈α⊗programs,␈α↔but␈α⊗this
␈↓ ↓H␈↓process␈α⊂is␈α⊂much␈α⊂better␈α⊂defined␈α⊂than␈α⊂blind␈α⊂debugging.␈α⊂On␈α⊂the␈α⊂other␈α⊂hand,␈α⊂if
␈↓ ↓H␈↓a␈α∩BEINGs␈α∩system␈α∩does␈α∩have␈α∩an␈α∩unexpected␈α∪bug␈α∩in␈α∩it,␈α∩it␈α∩may␈α∩not␈α∩be␈α∪able␈α∩to
␈↓ ↓H␈↓recover␈α↔from␈α↔it.␈α⊗One␈α↔way␈α↔to␈α⊗overcome␈α↔this␈α↔would␈α⊗be␈α↔to␈α↔include␈α⊗special
␈↓ ↓H␈↓recover-from-bugs BEINGs.

␈↓ ↓H␈↓The␈α formal␈α manipulation␈α systems␈α which␈α also␈α synthesize␈α code␈α are␈α so
␈↓ ↓H␈↓different␈α≠from␈α≠BEINGs,␈α≠that␈α≤it␈α≠is␈α≠difficult␈α≠to␈α≠compare␈α≤them.␈α≠ These
␈↓ ↓H␈↓logical␈α⊗systems␈α⊗(e.g.,␈α⊗[Luckham])␈α⊗attack␈α⊗an␈α⊗entirely␈α⊗different␈α⊗problem.
␈↓ ↓H␈↓Their␈α∪task␈α∪is␈α∪specified␈α∀rigorously␈α∪in␈α∪advance,␈α∪and␈α∪they␈α∀proceed␈α∪formally
␈↓ ↓H␈↓to␈α∩search␈α∪for␈α∩a␈α∪solution␈α∩program.␈α∪ BEINGs␈α∩are␈α∪designed␈α∩to␈α∪work␈α∩on␈α∪a␈α∩much
␈↓ ↓H␈↓higher␈α∀level,␈α∪heuristically.␈α∀ Each␈α∪action␈α∀is␈α∪implicitly␈α∀justified␈α∀by␈α∪the
␈↓ ↓H␈↓fact␈α∀that␈α∀the␈α∀user␈α∀can␈α∀later␈α∀describe␈α∀to␈α∀the␈α∀system␈α∀what␈α∀is␈α∀undesirable
␈↓ ↓H␈↓about␈α∪the␈α∪program␈α∪it's␈α∪generated.␈α∪BEINGs␈α∪should␈α∪thus␈α∪be␈α∪tolerant␈α∪of␈α∩user
␈↓ ↓H␈↓ambiguity␈α$and␈α#error.␈α$ Also,␈α#BEINGs␈α$are␈α#not␈α$limited␈α$to␈α#automatic
␈↓ ↓H␈↓programming.

␈↓ ↓H␈↓Like␈α⊂␈↓βany␈↓␈α⊂AP␈α⊃system␈α⊂which␈α⊂writes␈α⊃structured␈α⊂programs,␈α⊂the␈α⊃external␈α⊂behavior
␈↓ ↓H␈↓of␈α⊃a␈α∩BEINGs␈α⊃system␈α⊃applied␈α∩to␈α⊃this␈α⊃task␈α∩is␈α⊃reminiscent␈α⊃of␈α∩macro␈α⊃expansion
␈↓ ↓H␈↓regardless␈α∨of␈α∨␈↓βwhat␈↓␈α≡the␈α∨internal␈α∨BEING␈α≡interactions␈α∨are.␈α∨ One␈α≡major
␈↓ ↓H␈↓distinction␈α~between␈α~the␈α~two␈α~concepts␈α≠is␈α~when␈α~and␈α~how␈α~the␈α≠macros␈α~are
␈↓ ↓H␈↓expanded.␈α,Traditional␈α,answers␈α,are:␈α,at␈α,compile␈α,time,␈α,by␈α,rigid
␈↓ ↓H␈↓substitutions.␈α⊂ BEINGs␈α⊂systems␈α⊂expand␈α⊂their␈α⊂"macros"␈α⊂at␈α⊂times␈α⊂they␈α⊂choose,
␈↓ ↓H␈↓using␈α∀knowledge␈α∃gleaned␈α∀from␈α∀each␈α∃other␈α∀and␈α∀from␈α∃the␈α∀user.␈α∃For␈α∀example,
␈↓ ↓H␈↓consider␈α∀a␈α∃series␈α∀of␈α∀macro␈α∃calls␈α∀occurring␈α∀in␈α∃the␈α∀code:␈α∃(m1)(m2)(m3).␈α∀A
␈↓ ↓H␈↓macro␈α∪expander␈α∪could␈α∪expand␈α∪these␈α∪in␈α∪any␈α∪order,␈α∪and␈α∪the␈α∪three␈α∩activities
␈↓ ↓H␈↓could␈α∀go␈α∃on␈α∀simulatneously,␈α∀with␈α∃no␈α∀interference␈α∀or␈α∃change␈α∀in␈α∃the␈α∀final
␈↓ ↓H␈↓code.␈α∀BEINGs␈α∀would␈α∪try␈α∀to␈α∀find␈α∪some␈α∀task␈α∀common␈α∪to␈α∀all␈α∀three␈α∀calls,␈α∪and
␈↓ ↓H␈↓work␈α⊗on␈α⊗that␈α⊗first.␈α⊗The␈α⊗order␈α↔of␈α⊗which␈α⊗to␈α⊗first␈α⊗expand␈α⊗fully␈α↔would␈α⊗be
␈↓ ↓H␈↓carefully␈α→weighed,␈α→and␈α→during␈α→that␈α→expansion␈α→new␈α→information␈α→would␈α_be
␈↓ ↓H␈↓learned␈α⊂which␈α⊂could␈α⊂affect␈α⊂the␈α⊂expansions␈α⊂of␈α⊂the␈α⊂other␈α⊂two␈α⊂function␈α⊂calls.
␈↓ ↓H␈↓The␈α⊂final␈α⊂code␈α⊂would␈α⊂not␈α⊂simply␈α⊂be␈α⊂the␈α⊂APPEND␈α⊂of␈α⊂the␈α⊂expansions␈α⊂of␈α⊂m1,␈α⊂m2,
␈↓ ↓H␈↓m3.␈α⊂ As␈α⊂macro␈α⊂expansion␈α⊂schemes␈α⊂increase␈α⊂in␈α⊂sophistocation,␈α⊂it␈α⊂may␈α⊂someday
␈↓ ↓H␈↓be appropriate to refer to BEINGs as such a system.










␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 10␈↓ 	OTHEORY:  IDEAS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓␈↓↓4. REALITY: EXAMPLES␈↓

␈↓ ↓H␈↓This␈α∀section␈α∪presents␈α∀examples␈α∪of␈α∀the␈α∪following:␈α∀a␈α∀programming␈α∪knowledge
␈↓ ↓H␈↓BEING,␈α∀an␈α∀explanation␈α∀of␈α∀what␈α∀happens␈α∀when␈α∀a␈α∀BEING␈α∀is␈α∀called,␈α∀a␈α∀concept
␈↓ ↓H␈↓formation␈α~knowledge␈α→BEING,␈α~a␈α~description␈α→of␈α~a␈α→piece␈α~of␈α~the␈α→user-PUP6
␈↓ ↓H␈↓dialogue,␈α and␈α some␈α justification␈α for␈α using␈α functions,␈α call-by-name,
␈↓ ↓H␈↓demons,␈α∪and␈α∪assertions.␈α∪Although␈α∀these␈α∪examples␈α∪are␈α∪meant␈α∪to␈α∀clarify␈α∪the
␈↓ ↓H␈↓preceding␈α∩section's␈α⊃theoretical␈α∩ideas,␈α∩they␈α⊃are␈α∩all␈α⊃drawn␈α∩from␈α∩the␈α⊃actual
␈↓ ↓H␈↓PUP6 system.

␈↓ ↓H␈↓4.1.␈α+ OBTAIN_USABLE_INFORMATION␈α+is␈α*a␈α+typical␈α+high-level,␈α*domain-
␈↓ ↓H␈↓independent␈α∃BEING.␈α⊗ The␈α∃WHEN␈α∃part␈α⊗consists␈α∃of␈α∃predicate␈α⊗"feelers"␈α∃which
␈↓ ↓H␈↓sample␈α_the␈α_world␈α_and␈α_report␈α_their␈α_qualities␈α_numerically.␈α_ A␈α_reason␈α_is
␈↓ ↓H␈↓supplied␈α∪with␈α∪each␈α∪feeler:␈α∪an␈α∪English␈α∪sentence␈α∪stored␈α∪for␈α∪the␈α∪benefit␈α∩of
␈↓ ↓H␈↓inquisitive␈α↔users.␈α↔ The␈α_numbers␈α↔are␈α↔then␈α↔simply␈α_added␈α↔to␈α↔decide␈α_how␈α↔a
␈↓ ↓H␈↓propos␈α⊃the␈α∩BEING␈α⊃is␈α∩at␈α⊃present.␈α∩ This␈α⊃scheme␈α∩is␈α⊃adequate␈α∩but␈α⊃undesirable;
␈↓ ↓H␈↓one␈α∀would␈α∃like␈α∀them␈α∀to␈α∃discuss␈α∀descriptions␈α∀of␈α∃what␈α∀they␈α∃encounter;␈α∀but
␈↓ ↓H␈↓the␈α⊂WHEN␈α⊂part␈α⊂is␈α⊂used␈α⊂only␈α⊂to␈α⊂break␈α⊂ties␈α⊂between␈α⊂BEINGs␈α⊂vying␈α⊂for␈α⊂control,
␈↓ ↓H␈↓and␈α⊃it␈α⊃usually␈α⊃doesn't␈α∩matter␈α⊃what␈α⊃order␈α⊃they␈α∩go␈α⊃in.␈α⊃ Thus␈α⊃a␈α∩simple,␈α⊃fast
␈↓ ↓H␈↓method␈α↔of␈α↔selection␈α↔suffices.␈α↔ This␈α↔particular␈α↔BEING␈α↔has␈α_feelers␈α↔which
␈↓ ↓H␈↓respond␈α∩that␈α∩it␈α∩is␈α∩␈↓βalways␈↓␈α∪an␈α∩undesirable␈α∩(with␈α∩weight␈α∩-10;␈α∩see␈α∪the␈α∩actual
␈↓ ↓H␈↓WHEN␈α∪part␈α∪on␈α∪page␈α∪12)␈α∪thing␈α∪to␈α∪do,␈α∪but␈α∪␈↓βmay␈↓␈α∪be␈α∪indicated␈α∪(+111)␈α∪if␈α∪there
␈↓ ↓H␈↓exists␈α⊃new␈α∩but␈α⊃not␈α∩yet␈α⊃usable␈α∩information.␈α⊃The␈α∩possible␈α⊃final␈α∩WHEN␈α⊃values
␈↓ ↓H␈↓are␈α∩thus␈α∩111,␈α∪101,␈α∩and␈α∩-10.␈α∪These␈α∩numbers,␈α∩like␈α∩all␈α∪the␈α∩parts␈α∩of␈α∪all␈α∩the
␈↓ ↓H␈↓BEINGs initally in PUP6, were decided upon and inserted by hand.

␈↓ ↓H␈↓The␈α_IDEN␈α_parts␈α_are␈α_collected␈α_together␈α_into␈α_a␈α_large␈α_translation␈α_table.
␈↓ ↓H␈↓When␈α∪a␈α∪form␈α∪␈↓βLI␈↓␈α∪must␈α∪be␈α∩translated,␈α∪the␈α∪TRANSLATE␈α∪BEING␈α∪goes␈α∪through␈α∩this
␈↓ ↓H␈↓table,␈α⊃asking␈α∩each␈α⊃IDEN␈α⊃part␈α∩if␈α⊃it␈α∩claims␈α⊃to␈α⊃recognize␈α∩␈↓βLI␈↓.␈α⊃Each␈α∩IDEN␈α⊃runs
␈↓ ↓H␈↓its␈α∩own␈α⊃little␈α∩program,␈α∩typically␈α⊃some␈α∩type␈α∩of␈α⊃pattern␈α∩match␈α∩involving␈α⊃␈↓βLI␈↓
␈↓ ↓H␈↓and␈α↔the␈α↔state␈α⊗of␈α↔the␈α↔world,␈α⊗to␈α↔answer␈α↔this␈α⊗question.␈α↔ Some␈α↔measure␈α⊗of
␈↓ ↓H␈↓goodness␈α⊃of␈α∩match␈α⊃is␈α⊃also␈α∩reported.␈α⊃ If␈α⊃there␈α∩is␈α⊃more␈α⊃than␈α∩one␈α⊃responder,
␈↓ ↓H␈↓CHOOSE-FROM␈α⊃picks␈α∩the␈α⊃one␈α∩with␈α⊃the␈α∩highest␈α⊃priority␈α∩of␈α⊃match.␈α∩ The␈α⊃winner
␈↓ ↓H␈↓runs␈α⊃a␈α∩little␈α⊃program␈α∩which␈α⊃ultimately␈α∩returns␈α⊃a␈α∩BEING-call␈α⊃or␈α∩a␈α⊃constant
␈↓ ↓H␈↓as␈α⊂the␈α⊂translated␈α⊂value␈α⊂of␈α⊃␈↓βLI␈↓.␈α⊂This␈α⊂program␈α⊂might␈α⊂call␈α⊂other␈α⊃BEINGs,␈α⊂often
␈↓ ↓H␈↓calls␈α⊂TRANSLATE␈α⊂several␈α⊂times␈α⊂recursively␈α⊃on␈α⊂parts␈α⊂of␈α⊂␈↓βLI␈↓.␈α⊂ Now␈α⊃examine␈α⊂the
␈↓ ↓H␈↓IDEN␈α∀part␈α∪of␈α∀the␈α∪OBTAIN_USABLE_INFORMATION␈α∀BEING␈α∪(next␈α∀page).␈α∀ There␈α∪are
␈↓ ↓H␈↓just␈α≤two␈α≠classes␈α≤of␈α≤phrases␈α≠that␈α≤this␈α≤BEING␈α≠can␈α≤recognize.␈α≤ If␈α≠two
␈↓ ↓H␈↓conditions␈α→are␈α→met,␈α→it␈α→says␈α→to␈α→␈↓βcall␈↓␈α→OBTAIN-USABLE-INFORMATION␈α→with,␈α_as
␈↓ ↓H␈↓argument,␈α⊂the␈α⊂result␈α⊂of␈α⊂calling␈α⊃TRANSLATE␈α⊂on␈α⊂the␈α⊂second␈α⊂element␈α⊂of␈α⊃␈↓βLI␈↓.␈α⊂ If
␈↓ ↓H␈↓some␈α⊃BEING␈α⊃or␈α⊃user␈α∩wants␈α⊃to␈α⊃find␈α⊃out␈α∩more␈α⊃about␈α⊃anything,␈α⊃then␈α∩this␈α⊃BEING
␈↓ ↓H␈↓can be called with that thing as argument.

␈↓ ↓H␈↓The␈α⊃EFFECTS␈α∩parts␈α⊃of␈α⊃each␈α∩BEING␈α⊃are␈α⊃similarly␈α∩collected␈α⊃into␈α⊃one␈α∩table␈α⊃to
␈↓ ↓H␈↓facilitate␈α∃asking␈α∃all␈α∃BEINGs␈α∃simultaneously␈α∀"Can␈α∃you␈α∃cause␈α∃X␈α∃to␈α∀occur?"
␈↓ ↓H␈↓Each␈α⊂EFFECTS␈α⊂part␈α⊂examines␈α⊂X␈α⊂and␈α⊂the␈α⊂world,␈α⊂and␈α⊂either␈α⊂replies␈α⊂No,␈α⊂or␈α⊂else
␈↓ ↓H␈↓returns␈α→a␈α→little␈α→program␈α→(involving␈α→calls␈α→and␈α→constants)␈α→which␈α_should


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 11␈↓ 	 REALITY:  EXAMPLES
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓produce␈α≡the␈α≡effect,␈α≡with␈α∨a␈α≡certain␈α≡probability.␈α≡ This␈α∨program␈α≡will
␈↓ ↓H␈↓probably␈α⊂involve␈α⊂a␈α⊂call␈α⊂to␈α⊂the␈α⊂BEING␈α⊂itself.␈α⊂The␈α⊂BEING␈α⊂below␈α⊂shows␈α⊂that␈α⊂it
␈↓ ↓H␈↓should␈α⊃be␈α∩called␈α⊃to␈α∩acheive␈α⊃the␈α∩existence␈α⊃of␈α∩new,␈α⊃usable␈α∩information␈α⊃(see
␈↓ ↓H␈↓the MAIN:EFFECTS part, page 12).

␈↓ ↓H␈↓The␈α∀WHAT,␈α∀HOW,␈α∪and␈α∀WHY␈α∀parts␈α∪are␈α∀mainly␈α∀for␈α∪the␈α∀user's␈α∀benefit.␈α∀ When␈α∪a
␈↓ ↓H␈↓choice␈α⊗between␈α↔BEINGs␈α⊗must␈α↔be␈α⊗made,␈α⊗the␈α↔WHEN,␈α⊗AFFECTS,␈α↔and␈α⊗COMPLEXITY-
␈↓ ↓H␈↓VECTOR␈α⊂parts␈α⊂are␈α⊂queried.␈α⊂ If␈α⊂a␈α⊂new,␈α⊂manipulated␈α⊂version␈α⊂of␈α⊂the␈α⊂BEING␈α⊂must
␈↓ ↓H␈↓be␈α⊂created,␈α⊂the␈α⊂SPECIALIZATIONS,␈α⊂ENCODABLE,␈α⊂DATA-STRUCTURE,␈α⊂PREDICATE,␈α⊂and
␈↓ ↓H␈↓FORM-CHANGING␈α⊗parts␈α↔might␈α⊗be␈α↔relevant.␈α⊗ If␈α⊗the␈α↔BEING␈α⊗fails,␈α↔some␈α⊗BEING
␈↓ ↓H␈↓speicified in the ALTERNATIVES or GENERALIZATIONS parts might be tried.

␈↓ ↓H␈↓In␈α↔the␈α↔current␈α_case,␈α↔the␈α↔COMPLEXITY-VECTOR␈α↔says␈α_that␈α↔it␈α↔is␈α_of␈α↔average
␈↓ ↓H␈↓difficulty␈α∪to␈α∪call,␈α∩its␈α∪descendants␈α∪may␈α∩(.5␈α∪chance)␈α∪call␈α∩it␈α∪back,␈α∪it␈α∩has
␈↓ ↓H␈↓an␈α∀average␈α∀chance␈α∪of␈α∀success␈α∀and␈α∪cost␈α∀of␈α∀attempting␈α∪it,␈α∀and␈α∀there␈α∀is␈α∪no
␈↓ ↓H␈↓(.1) good reason to defer it any longer.

␈↓ ↓H␈↓The␈α→AFFECTS␈α→part␈α→of␈α→the␈α→OBTAIN_USABLE_INFORMATION␈α→BEING␈α→is␈α→clear.␈α_One
␈↓ ↓H␈↓BEING is definitely called, and four others might be.

␈↓ ↓H␈↓The␈α∃absence␈α⊗of␈α∃some␈α∃parts,␈α⊗like␈α∃DATA_STRUCTURE,␈α∃PREDICATE,␈α⊗and␈α∃NLAMBDA,
␈↓ ↓H␈↓indicate␈α∃that␈α∃these␈α∃qualities␈α∃don't␈α∀apply.␈α∃ The␈α∃absence␈α∃of␈α∃other␈α∀parts,
␈↓ ↓H␈↓like␈α(SPECIALIZATIONS␈α(and␈α(ALTERNATIVES,␈α(indicate␈α(only␈α(a␈α(lack␈α(of
␈↓ ↓H␈↓thoroughness in filling out unneeded BEING parts.

␈↓ ↓H␈↓The␈α⊂META-CODE␈α⊂says␈α⊂to␈α⊂choose␈α⊂from␈α⊂the␈α⊂following␈α⊂four␈α⊂alternatives,␈α⊂each␈α⊂of
␈↓ ↓H␈↓which␈α∀is␈α∪itself␈α∀a␈α∪BEING:␈α∀Get_Brand_New_Information␈α∪(in␈α∀English,␈α∀from␈α∪the
␈↓ ↓H␈↓user),␈α Translate␈α something␈α (transform␈α from␈α English␈α to␈α BEING-calls),
␈↓ ↓H␈↓Analyze_The_Implications␈α#(of␈α#some␈α#existing,␈α$translated␈α#information),
␈↓ ↓H␈↓Extract_a_Relevant_Subset␈α≠(of␈α≠the␈α~existing␈α≠information)␈α≠to␈α~concentrate
␈↓ ↓H␈↓upon.␈α⊂ Calls␈α⊂are␈α⊂nondeterministic␈α⊂only␈α⊂when␈α⊂the␈α⊂BEING␈α⊂doesn't␈α⊂know␈α⊂exactly
␈↓ ↓H␈↓which␈α∪BEING␈α∪to␈α∀call.␈α∪If␈α∪the␈α∀␈↓βset␈↓␈α∪of␈α∪possible␈α∪choices␈α∀is␈α∪known,␈α∪as␈α∀in␈α∪this
␈↓ ↓H␈↓case,␈α∀then␈α∃CHOOSE-FROM␈α∀is␈α∀called␈α∃with␈α∀the␈α∀choice␈α∃set␈α∀explicit.␈α∃ If␈α∀even
␈↓ ↓H␈↓this␈α⊂isn't␈α⊂known,␈α⊂then␈α⊂CHOOSE-FROM␈α⊂must␈α⊂query␈α⊂the␈α⊂EFFECTS␈α⊂parts␈α⊂of␈α⊂all␈α⊂the
␈↓ ↓H␈↓BEINGs in the system.

␈↓ ↓H␈↓Below␈α∪are␈α∪exhibited␈α∪the␈α∪actual␈α∪representation␈α∪of␈α∪this␈α∪BEING␈α∪in␈α∪PUP6,␈α∩and
␈↓ ↓H␈↓the function which would be executed if it were ␈↓βcalled␈↓.


␈↓ ↓H␈↓∧␈↓β␈↓&PART␈↓'β    ␈↓&actual value of the part for OBTAIN:USABLE:INFORMATION␈↓'β ␈↓∧

␈↓ ↓H␈↓∧IDEN ((if you see: (AND (EQUAL (CAR LI)
␈↓ ↓H␈↓∧                                OBTAIN:USABLE:INFORMATION)
␈↓ ↓H␈↓∧                        (EQUAL (LENGTH LI)
␈↓ ↓H␈↓∧                                 2))
␈↓ ↓H␈↓∧       then return: (OBTAIN:USABLE:INFORMATION (TRANSLATE (CADR LI))))
␈↓ ↓H␈↓∧      (if you see: (MATCH ( FIND OUT MORE ABOUT ANY1)   LI)
␈↓ ↓H␈↓∧       then return: (OBTAIN:USABLE:INFORMATION ANY1)))

␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 12␈↓ 	 REALITY:  EXAMPLES
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓∧BEING T
␈↓ ↓H␈↓∧EXPLICIT:ARGS (U)
␈↓ ↓H␈↓∧WHAT ( OBTAIN SOME INFORMATION WHICH CAN BE USED)
␈↓ ↓H␈↓∧HOW ( OBTAIN NEW FACTS ABOUT OLD INFORMATION, OR OBTAIN TOTALLY
␈↓ ↓H␈↓∧     NEW INFORMATION)
␈↓ ↓H␈↓∧WHY ( PUP HAS NO MORE INFORMATION THAT IT CAN USE TO PROGRESS)
␈↓ ↓H␈↓∧WHEN ((if T then add in -10 (SINCE THIS IS AN EXPONENTIALLY-GROWING,
␈↓ ↓H␈↓∧                                BAD THING TO DO IN GENERAL))
␈↓ ↓H␈↓∧      (if NEW:INFO:LIST then add in 111
␈↓ ↓H␈↓∧                (BECAUSE WE SHOULD WORK ON UNASSIMILATED NEW
␈↓ ↓H␈↓∧                              INFORMATION IF THERE IS ANY)))
␈↓ ↓H␈↓∧META:CODE (DO
␈↓ ↓H␈↓∧                 (CHOOSE:FROM ((TRANSLATE U)
␈↓ ↓H␈↓∧                               (GET:NEW:INFORMATION U)
␈↓ ↓H␈↓∧                               (ANALYZE:IMPLICATIONS U)
␈↓ ↓H␈↓∧                               (EXTRACT:RELEVANT:SUBSET U)))
␈↓ ↓H␈↓∧           BECAUSE
␈↓ ↓H␈↓∧                 (WE CAN ONLY TRY TO OBTAIN USABLE
␈↓ ↓H␈↓∧                            INFORMATION IN ONE WAY AT A TIME))
␈↓ ↓H␈↓∧EXPLICIT:ARGS:CHECK T
␈↓ ↓H␈↓∧MAIN:EFFECTS ((to get (NEW INFO ANY1)
␈↓ ↓H␈↓∧               do (OBTAIN:USABLE:INFORMATION ( ANY1)))
␈↓ ↓H␈↓∧              (to get (USABLE INFO ANY1)
␈↓ ↓H␈↓∧               do (OBTAIN:USABLE:INFORMATION ( ANY1))))
␈↓ ↓H␈↓∧AFFECTS       ( (CHOOSE:FROM CALLED)
␈↓ ↓H␈↓∧                (TRANSLATE POSSIBLE:CALLED)
␈↓ ↓H␈↓∧                (GET:NEW:INFORMATION POSSIBLE:CALLED)
␈↓ ↓H␈↓∧                (ANALYZE:IMPLICATIONS POSSIBLE:CALLED)
␈↓ ↓H␈↓∧                (EXTRACT:RELEVANT:SUBSET POSSIBLE:CALLED) )
␈↓ ↓H␈↓∧COMPLEXITY:VECTOR (.5 .5 .5 .5 .1)

␈↓ ↓H␈↓        4.2. When a BEING is ␈↓βcalled␈↓, its parts are assembled into a
␈↓ ↓H␈↓function which is then executed. Here is the ␈↓βFUNCTIONAL␈↓ form of the
␈↓ ↓H␈↓OBTAIN:USABLE:INFORMATION   BEING:

␈↓ ↓H␈↓∧(OBTAIN:USABLE:INFORMATION
␈↓ ↓H␈↓∧  (LAMBDA (U FN:VALUE FINAL:CO:REQ)
␈↓ ↓H␈↓∧      (PROG1
␈↓ ↓H␈↓∧          (AND
␈↓ ↓H␈↓∧              (SETQ BEING:STACK (CONS OBTAIN:USABLE:INFORMATION BEING:STACK))
␈↓ ↓H␈↓∧              (PUT OBTAIN:USABLE:INFORMATION SPEC:WHY BECAUSE)
␈↓ ↓H␈↓∧              (EVERY (APPEND CURRENT:DEMONS USER:INTERRUPT:DEMONS)
␈↓ ↓H␈↓∧                     (QUOTE APPLY*))
␈↓ ↓H␈↓∧              (SETQ BECAUSE
␈↓ ↓H␈↓∧                   (QUOTE (WE CAN ONLY TRY TO OBTAIN USABLE
␈↓ ↓H␈↓∧                              INFORMATION IN ONE WAY AT A TIME)))
␈↓ ↓H␈↓∧              (CHOOSE:FROM (QUOTE ((TRANSLATE U)
␈↓ ↓H␈↓∧                                   (GET:NEW:INFORMATION U)
␈↓ ↓H␈↓∧                                   (ANALYZE:IMPLICATIONS U)
␈↓ ↓H␈↓∧                                   (EXTRACT:RELEVANT:SUBSET U)))))
␈↓ ↓H␈↓∧          (SETQ BEING:STACK (CDR BEING:STACK)))))

␈↓ ↓H␈↓The␈α⊗process␈α⊗of␈α⊗assembling␈α⊗the␈α∃BEING␈α⊗parts␈α⊗into␈α⊗a␈α⊗function␈α⊗is␈α∃straight-
␈↓ ↓H␈↓forward.␈α∃ First,␈α∃the␈α∃explicit␈α∃arguments␈α∀(those␈α∃global␈α∃to␈α∃the␈α∃BEING)␈α∀are


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 13␈↓ 	 REALITY:  EXAMPLES
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓bound.␈α≥The␈α≥implicit␈α≥arguments␈α≥(those␈α≤local␈α≥to␈α≥the␈α≥BEING,␈α≥like␈α≤PROG
␈↓ ↓H␈↓variables)␈α⊂are␈α⊂initialized.␈α⊂The␈α⊂name␈α⊂of␈α⊂the␈α⊂BEING␈α⊂is␈α⊂pushed␈α⊂onto␈α⊂the␈α⊂BEING
␈↓ ↓H␈↓control␈α⊂stack␈α⊂(pointing␈α⊂to␈α⊂its␈α⊂caller),␈α⊂and␈α⊂any␈α⊂newly-activated␈α⊂demons␈α⊂are
␈↓ ↓H␈↓pushed␈α↔onto␈α↔the␈α↔demon␈α↔stack.␈α↔ The␈α↔ARGS-CHECK␈α↔predicates␈α_are␈α↔evaluated.
␈↓ ↓H␈↓Then␈α~PUP6␈α~works␈α~to␈α~make␈α≠each␈α~PRE-REQUISITE␈α~true␈α~in␈α~the␈α≠world.␈α~ Each
␈↓ ↓H␈↓COMMENT␈α≤is␈α≤evaluated,␈α≤then␈α≤the␈α≤CO-REQUISITES,␈α≤META-CODE,␈α≤and␈α≤current
␈↓ ↓H␈↓demons␈α∀all␈α∪are␈α∀executed␈α∪in␈α∀pseudo-parallel.␈α∪ Each␈α∀POST-REQUISITE␈α∀is␈α∪then
␈↓ ↓H␈↓satisfied.␈α⊂ Since␈α⊂these␈α⊂activities␈α⊂are␈α⊂all␈α⊂embedded␈α⊂in␈α⊂an␈α⊂AND,␈α⊂any␈α⊂of␈α⊂them
␈↓ ↓H␈↓may␈α⊃cause␈α⊃the␈α⊃entire␈α∩BEING␈α⊃to␈α⊃halt␈α⊃and␈α∩fail,␈α⊃simply␈α⊃by␈α⊃returning␈α∩NIL.␈α⊃ In
␈↓ ↓H␈↓both␈α∪cases,␈α∪just␈α∩before␈α∪exiting,␈α∪the␈α∩demon␈α∪stack␈α∪is␈α∩popped␈α∪and␈α∪the␈α∩BEING
␈↓ ↓H␈↓stack␈α≡is␈α∨updated␈α≡(usually␈α∨just␈α≡popped),␈α≡and␈α∨control␈α≡passes␈α∨to␈α≡the
␈↓ ↓H␈↓delegated␈α⊃BEING␈α∩(usually␈α⊃the␈α⊃one␈α∩who␈α⊃called␈α⊃this␈α∩BEING,␈α⊃at␈α⊃the␈α∩state␈α⊃when
␈↓ ↓H␈↓he␈α∀called␈α∃it.)␈α∀A␈α∀fancy␈α∃context␈α∀mechanism␈α∀was␈α∃available␈α∀but␈α∃not␈α∀actually
␈↓ ↓H␈↓needed.

␈↓ ↓H␈↓The␈α⊗function␈α⊗which␈α⊗assembled␈α⊗all␈α∃the␈α⊗BEINGs␈α⊗exploited␈α⊗the␈α⊗fact␈α⊗that␈α∃it
␈↓ ↓H␈↓operated␈α⊃only␈α⊃at␈α⊃system␈α⊃load␈α⊃time.␈α∩Thus␈α⊃if␈α⊃the␈α⊃BEING␈α⊃had␈α⊃no␈α⊃new␈α∩DEMONs␈α⊃to
␈↓ ↓H␈↓activate,␈α"all␈α"the␈α#corresponding␈α"demon-stack␈α"manipulations␈α#could␈α"be
␈↓ ↓H␈↓omitted.␈α∩Optimizations␈α∩like␈α∩these␈α⊃are␈α∩clear␈α∩from␈α∩comparing␈α∩the␈α⊃functional
␈↓ ↓H␈↓form␈α⊂and␈α⊂the␈α⊂description␈α⊂of␈α⊂how␈α⊂it␈α⊂should␈α⊂be␈α⊂created␈α⊂(see␈α⊂above).␈α⊂ Another
␈↓ ↓H␈↓example␈α→in␈α→this␈α_BEING␈α→is␈α→that␈α→no␈α_CO-REQUISITES␈α→occur,␈α→so␈α→no␈α_parallel
␈↓ ↓H␈↓processing need be simulated.

␈↓ ↓H␈↓4.3.␈α⊂PARTITION_A_DOMAIN␈α⊂is␈α⊂a␈α⊂high-level,␈α⊂domain-specific␈α⊂BEING␈α⊂whose␈α⊂basic
␈↓ ↓H␈↓idea␈α∀is␈α∀to␈α∪divide␈α∀up␈α∀a␈α∪space␈α∀into␈α∀categories.␈α∪ Only␈α∀two␈α∀BEING␈α∀parts␈α∪are
␈↓ ↓H␈↓filled␈α∀in␈α∀here␈α∀which␈α∀were␈α∀absent␈α∀from␈α∀OBTAIN_USABLE_INFORMATION;␈α∀namely,
␈↓ ↓H␈↓SPECIALIZATIONS␈α⊂and␈α⊂DEMONS.␈α⊂ The␈α⊂SPECIALIZATIONS␈α⊂part␈α⊂says␈α⊂that␈α⊂to␈α⊂write␈α⊂a
␈↓ ↓H␈↓specific␈α⊂version␈α⊂of␈α⊂itself,␈α⊂a␈α⊂few␈α⊂decisions␈α⊂must␈α⊂be␈α⊂made.␈α⊂The␈α⊂results␈α⊂will
␈↓ ↓H␈↓then␈α∪indicate␈α∪what␈α∩pieces␈α∪of␈α∪code␈α∩get␈α∪assembled␈α∪together␈α∩to␈α∪form␈α∪the␈α∩new
␈↓ ↓H␈↓BEING.␈α~ The␈α~partition␈α~may␈α~be␈α≠only␈α~partial␈α~(an␈α~element␈α~of␈α≠the␈α~domain
␈↓ ↓H␈↓belongs␈α∀to␈α∀no␈α∀class␈α∀of␈α∀the␈α∀partition),␈α∀only␈α∀weak␈α∀(an␈α∀element␈α∀belongs␈α∀to
␈↓ ↓H␈↓more␈α∩than␈α⊃one␈α∩class),␈α∩and,␈α⊃most␈α∩importantly,␈α⊃the␈α∩specialized␈α∩BEING␈α⊃should
␈↓ ↓H␈↓work␈α⊃by␈α∩repeatedly␈α⊃doing␈α∩some␈α⊃of␈α∩the␈α⊃following␈α∩three␈α⊃activities:␈α∩accept␈α⊃a
␈↓ ↓H␈↓class-name␈α⊂from␈α⊂the␈α⊂user␈α⊂and␈α⊂guess␈α⊂some␈α⊂of␈α⊂its␈α⊂elements,␈α⊂accept␈α⊂an␈α⊂element
␈↓ ↓H␈↓from␈α∃the␈α∀user␈α∃and␈α∀try␈α∃to␈α∃guess␈α∀which␈α∃class␈α∀it␈α∃belongs␈α∀to,␈α∃or␈α∃accept␈α∀an
␈↓ ↓H␈↓<element,␈α≤class-name>␈α≤pair.␈α≤Other␈α≤BEINGs␈α≤know␈α≤about␈α≤these␈α≤accepting,
␈↓ ↓H␈↓guessing, checking activities.

␈↓ ↓H␈↓The␈α∪DEMONS␈α∪part␈α∩says␈α∪that␈α∪during␈α∩the␈α∪partitioning,␈α∪the␈α∩only␈α∪new␈α∪demon␈α∩to
␈↓ ↓H␈↓keep␈α→active␈α→is␈α→the␈α→one␈α→called␈α→Fringe_of_Consciousness.␈α→ This␈α→name␈α_was
␈↓ ↓H␈↓chosen␈α⊂because␈α⊂its␈α⊂function␈α⊂is␈α⊂similar␈α⊂to␈α⊂the␈α⊂"impossibility"␈α⊂mentioned␈α⊂in
␈↓ ↓H␈↓[Dreyfus].␈α∪ In␈α∪the␈α∩course␈α∪of␈α∪writing␈α∩GI,␈α∪the␈α∪system␈α∩learns␈α∪that␈α∪the␈α∩main
␈↓ ↓H␈↓task␈α_is␈α_one␈α_of␈α_grammatical␈α_inference.␈α_ The␈α_Grammatical_Inference␈α_BEING
␈↓ ↓H␈↓then␈α⊂asserts␈α⊂that␈α⊂if␈α⊂the␈α⊂user␈α⊂ever␈α⊂mentions␈α⊂the␈α⊂word␈α⊂TEST,␈α⊂he␈α⊂may␈α⊂actually
␈↓ ↓H␈↓mean␈α∃PARSE.␈α∀ This␈α∃is␈α∀placed␈α∃in␈α∃the␈α∀IDEN␈α∃part␈α∀of␈α∃the␈α∀TEST␈α∃BEING,␈α∃and␈α∀is
␈↓ ↓H␈↓therefore␈α,only␈α,demonized,␈α,waiting␈α,on␈α,the␈α,periphery␈α,of␈α,PUP6's
␈↓ ↓H␈↓concentration.␈α→ It␈α→is␈α_in␈α→fact␈α→triggered␈α→later␈α_in␈α→the␈α→dialogue,␈α→as␈α_an
␈↓ ↓H␈↓inference surprising to the user.

␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 14␈↓ 	 REALITY:  EXAMPLES
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓4.4.␈α⊂ The␈α⊂dialogue␈α⊂to␈α⊂synthesize␈α⊂CF␈α⊂begins␈α⊂by␈α⊂PUP6␈α⊂asking␈α⊂the␈α⊂user␈α⊂for␈α⊂any
␈↓ ↓H␈↓task.␈α∞ The␈α∞user␈α∞replies,␈α∞␈↓βWrite␈α∞a␈α
program␈α∞which␈α∞does␈α∞concept␈α∞formation␈↓.␈α∞There␈α
are
␈↓ ↓H␈↓many␈α_decisions␈α_that␈α_PUP6␈α_knows␈α_about␈α_in␈α_writing␈α_a␈α_specialized␈α_concept
␈↓ ↓H␈↓formation␈α≥program␈α≥[Hempel],␈α≥and␈α≥it␈α≤manages␈α≥to␈α≥defer␈α≥them␈α≥all.␈α≤ For
␈↓ ↓H␈↓example,␈α∩it␈α∩must␈α∩choose␈α∩between␈α∩classificatory,␈α∩comparative,␈α∩and␈α∩metrical
␈↓ ↓H␈↓concept␈α≤formation.␈α≥Since␈α≤all␈α≥three␈α≤involve␈α≥partitioning␈α≤a␈α≥domain␈α≤of
␈↓ ↓H␈↓examples,␈α∪PUP6␈α∪decides␈α∩it␈α∪can␈α∪defer␈α∩this␈α∪choice␈α∪until␈α∩after␈α∪code␈α∪for␈α∩the
␈↓ ↓H␈↓partitioning␈α⊗is␈α↔synthesized.␈α⊗ The␈α↔effort␈α⊗of␈α⊗the␈α↔system␈α⊗is␈α↔now␈α⊗directed
␈↓ ↓H␈↓toward␈α⊃this␈α⊃"piece"␈α⊃of␈α∩the␈α⊃program.␈α⊃ When␈α⊃it␈α∩is␈α⊃completed,␈α⊃an␈α⊃hour␈α∩or␈α⊃two
␈↓ ↓H␈↓later,␈α∩the␈α∪system␈α∩asks␈α∪the␈α∩user␈α∪to␈α∩make␈α∪this␈α∩decision.␈α∪When␈α∩he␈α∪picks␈α∩the
␈↓ ↓H␈↓first␈α→alternative,␈α→which␈α~involves␈α→␈↓βonly␈↓␈α→partitioning,␈α→the␈α~system␈α→prints
␈↓ ↓H␈↓that␈α_it␈α_has␈α_finished␈α_the␈α_entire␈α_CF␈α_task,␈α_and␈α_dumps␈α_the␈α_newly␈α_created
␈↓ ↓H␈↓BEINGs onto a file.

␈↓ ↓H␈↓4.5.␈α⊃Earlier,␈α∩the␈α⊃claim␈α⊃was␈α∩made␈α⊃that␈α⊃the␈α∩presence␈α⊃of␈α⊃popular␈α∩AI␈α⊃language
␈↓ ↓H␈↓features␈α∃did␈α∃not␈α∃detract␈α∃from␈α∀the␈α∃combinatorial␈α∃behavior␈α∃of␈α∃the␈α∀system,
␈↓ ↓H␈↓since␈α_BEINGs␈α_subsume␈α_each␈α_mechanaism␈α_used.␈α_This␈α_will␈α_now␈α_be␈α_sketched.
␈↓ ↓H␈↓Direct␈α∀call␈α∀by␈α∀name␈α∀may␈α∀be␈α∀viewed␈α∀as␈α∀a␈α∀trivial␈α∀type␈α∀of␈α∀pattern-directed
␈↓ ↓H␈↓call,␈α∀where␈α∀each␈α∪BEING␈α∀can␈α∀recognize␈α∪its␈α∀own␈α∀name.␈α∪See␈α∀the␈α∀IDEN␈α∀part␈α∪of
␈↓ ↓H␈↓the OBTAIN:USABLE:INFORMATION BEING, for example.

␈↓ ↓H␈↓A␈α⊂demon␈α⊂in␈α⊂PUP6␈α⊂is␈α⊂merely␈α⊂a␈α⊂function␈α⊂which␈α⊂gets␈α⊂executed␈α⊂periodically,␈α⊂and
␈↓ ↓H␈↓may␈α⊃occasionally␈α∩trigger␈α⊃a␈α⊃BEING.␈α∩This␈α⊃could␈α⊃be␈α∩replaced␈α⊃by␈α⊃a␈α∩BEING␈α⊃whose
␈↓ ↓H␈↓EXPLICIT:ARGS:CHECK␈α≠part␈α≤contains␈α≠the␈α≤triggering␈α≠predicate,␈α≤and␈α≠whose
␈↓ ↓H␈↓META:CODE␈α⊂is␈α⊂simply␈α⊂a␈α⊂call␈α⊂by␈α⊂name␈α⊂directly␈α⊂to␈α⊂the␈α⊂BEING␈α⊂which␈α⊂is␈α⊂supposed
␈↓ ↓H␈↓to be activated.

␈↓ ↓H␈↓An␈α∩assertion␈α∪can␈α∩be␈α∪viewed␈α∩as␈α∪a␈α∩BEING␈α∪containing␈α∩only␈α∪an␈α∩IDEN␈α∪part;␈α∩when
␈↓ ↓H␈↓the␈α≤BEING␈α≠recognizes␈α≤a␈α≤form␈α≠which␈α≤matches␈α≤it,␈α≠it␈α≤returns␈α≤the␈α≠fully
␈↓ ↓H␈↓instantiated assertion.

␈↓ ↓H␈↓A␈α⊂function␈α⊂is␈α⊂equivalent␈α⊂to␈α⊂a␈α⊂BEING␈α⊂with␈α⊂only␈α⊂META:CODE,␈α⊂ARGS,␈α⊂and␈α⊂NLAMBDA
␈↓ ↓H␈↓parts; one knows almost nothing about it before executing it.

␈↓ ↓H␈↓Notice␈α∪that␈α∪the␈α∪overheads␈α∀saved␈α∪by␈α∪these␈α∪mechanisms␈α∪are␈α∀substantial.␈α∪For
␈↓ ↓H␈↓example,␈α assertions␈α replace␈α an␈α entire␈α BEING␈α call␈α by␈α a␈α single␈α CDR
␈↓ ↓H␈↓evaluation.

␈↓ ↓H␈↓The␈α⊗reader␈α⊗may␈α⊗have␈α⊗observed␈α∃the␈α⊗static␈α⊗quality␈α⊗of␈α⊗these␈α⊗examples,␈α∃and
␈↓ ↓H␈↓wished␈α↔for␈α↔one␈α⊗of␈α↔BEINGs␈α↔in␈α⊗action,␈α↔passing␈α↔control␈α⊗back␈α↔and␈α↔forth␈α⊗in
␈↓ ↓H␈↓order␈α→to␈α→do␈α_something.␈α→But␈α→to␈α→present␈α_a␈α→reasonable␈α→example␈α→of␈α_BEINGs
␈↓ ↓H␈↓interacting,␈α→it␈α→is␈α→necessary␈α→to␈α→understand␈α→something␈α→about␈α→the␈α_target
␈↓ ↓H␈↓task.␈α∪ Thus␈α∪we␈α∪describe␈α∪PUP6␈α∪in␈α∪the␈α∪following␈α∪section,␈α∪including␈α∪how␈α∩the
␈↓ ↓H␈↓target task CF evolved. Then comes the dynamic example, in section 6.





␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 15␈↓ 	 REALITY:  EXAMPLES
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓␈↓↓5. THEORY: DESIGN␈↓

␈↓ ↓H␈↓A␈α↔highly␈α↔polished␈α_presentation␈α↔of␈α↔a␈α↔large␈α_system␈α↔omits␈α↔mention␈α_of␈α↔the
␈↓ ↓H␈↓design␈α∀and␈α∀implementation␈α∀mistakes.␈α∀ This␈α∀is␈α∀unfortunate;␈α∀many␈α∀decisions
␈↓ ↓H␈↓which␈α⊂seem␈α⊂arbitrary␈α⊂are␈α⊂the␈α⊂result␈α⊂of␈α⊂painful␈α⊂re-working,␈α⊂and␈α⊂conversely.
␈↓ ↓H␈↓The reader may relax; he will find nothing polished about this treatment.

␈↓ ↓H␈↓Once␈α↔the␈α↔task␈α↔(automatic␈α↔program␈α↔synthesis␈α↔from␈α↔specific␈α_dialogue)␈α↔was
␈↓ ↓H␈↓decided␈α∩upon,␈α∩considerable␈α∩attention␈α⊃was␈α∩spent␈α∩on␈α∩choosing␈α∩an␈α⊃appropriate
␈↓ ↓H␈↓domain␈α∀of␈α∪target␈α∀programs.␈α∪ The␈α∀choice,␈α∪inductive␈α∀inference␈α∀(II),␈α∪merits
␈↓ ↓H␈↓discussion.␈α∃ The␈α∃obvious␈α∃difficulty␈α∃appears␈α∀to␈α∃be␈α∃the␈α∃complexity␈α∃of␈α∀the
␈↓ ↓H␈↓programs␈α≠involved:␈α≠they␈α≠are␈α≤two␈α≠orders␈α≠of␈α≠magnitude␈α≠larger␈α≤than␈α≠any
␈↓ ↓H␈↓previously synthesized programs. But there are four big attractions:

␈↓ ↓H␈↓(i)␈α"A␈α!wide␈α"range␈α"of␈α!complexity␈α"exists,␈α!from␈α"a␈α"one-page␈α!sequence
␈↓ ↓H␈↓extrapolator to Meta-Dendral.

␈↓ ↓H␈↓(ii)␈α∩Each␈α⊃increasingly␈α∩sophisticated␈α∩II␈α⊃program␈α∩uses␈α⊃many␈α∩of␈α∩the␈α⊃concepts
␈↓ ↓H␈↓embodied in simpler II programs.

␈↓ ↓H␈↓(iii)␈α⊗If␈α⊗a␈α⊗super-human␈α⊗target␈α∃program␈α⊗is␈α⊗ever␈α⊗written,␈α⊗it␈α⊗could␈α∃itself
␈↓ ↓H␈↓contribute␈α⊂to␈α⊂the␈α⊂field␈α⊂of␈α⊂Automatic␈α⊂Programming!␈α⊂(This␈α⊂remark␈α⊂is␈α⊂humorous
␈↓ ↓H␈↓in the seventies, but may be commonplace someday.)

␈↓ ↓H␈↓(iv)␈α≥Since␈α≥people␈α≥(especially␈α≥those␈α≤who␈α≥write␈α≥AI␈α≥programs)␈α≥are␈α≤the
␈↓ ↓H␈↓inductive␈α∩inference␈α⊃experts,␈α∩our␈α∩reliance␈α⊃on␈α∩introspection␈α⊃is␈α∩as␈α∩valid␈α⊃--
␈↓ ↓H␈↓and potentially as valuable -- as chemists' protocols were to Dendral.

␈↓ ↓H␈↓After␈α"studying␈α"many␈α"sample␈α!programs␈α"from␈α"the␈α"II␈α"domain,␈α!sequence
␈↓ ↓H␈↓extrapolation␈α∀[Pilvar]␈α∪seemed␈α∀the␈α∪most␈α∀reasonable␈α∪beginning␈α∀task.␈α∀It␈α∪was
␈↓ ↓H␈↓quickly␈α⊃learned␈α∩that␈α⊃this␈α⊃was␈α∩too␈α⊃easy:␈α⊃humans␈α∩have␈α⊃only␈α⊃a␈α∩few␈α⊃techniques
␈↓ ↓H␈↓for␈α↔extrapolating␈α↔sequences,␈α↔and␈α↔a␈α↔very␈α↔limited␈α↔capacity␈α_for␈α↔composing
␈↓ ↓H␈↓them.␈α⊃ Thus␈α∩a␈α⊃rather␈α∩rigid␈α⊃sequence␈α∩extrapolator␈α⊃writer␈α∩may␈α⊃be␈α∩capable␈α⊃of
␈↓ ↓H␈↓generating␈α~a␈α→large␈α~class␈α~of␈α→super-human␈α~programs␈α→(see␈α~section␈α~4.2␈α→on
␈↓ ↓H␈↓Sequence-Extrapolator-Writer, in [Green]).

␈↓ ↓H␈↓The␈α≤next␈α≤candidates␈α≤were␈α≤grammatical␈α≤inference␈α≤and␈α≤concept␈α≤formation
␈↓ ↓H␈↓[Hempel].␈α∀ Determined␈α∃not␈α∀to␈α∀choose␈α∃too␈α∀simple␈α∀a␈α∃task␈α∀again,␈α∃the␈α∀latter
␈↓ ↓H␈↓program␈α⊃was␈α∩finally␈α⊃decided␈α∩upon.␈α⊃ The␈α∩particular␈α⊃target␈α∩was␈α⊃a␈α∩variant␈α⊃of
␈↓ ↓H␈↓[Winston].␈α⊗To␈α↔make␈α⊗the␈α↔goal␈α⊗more␈α⊗tractable,␈α↔certain␈α⊗parts␈α↔of␈α⊗Winston's
␈↓ ↓H␈↓description␈α⊂were␈α⊂ignored,␈α⊂namely␈α⊂the␈α⊂heuristic␈α⊂graph-matching␈α⊂section,␈α⊂and
␈↓ ↓H␈↓the␈α~uniformity␈α~requirement␈α~that␈α~relations␈α~on␈α~features␈α~be␈α~functionally
␈↓ ↓H␈↓indistinguishable␈α≠from␈α≠features.␈α~ This␈α≠last␈α≠phrase␈α~means␈α≠that␈α≠CF␈α~may
␈↓ ↓H␈↓internally␈α(store␈α((MUSTNOT␈α((SUPPORTS␈α(a␈α(b))␈α(differently␈α(from␈α(the
␈↓ ↓H␈↓representation of simple features like (TOUCHES a c).

␈↓ ↓H␈↓It␈α≥seems␈α≥instructive␈α≥now␈α≥to␈α≤describe␈α≥how␈α≥the␈α≥target␈α≥program␈α≤should


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 16␈↓ 	@THEORY:  DESIGN
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓operate.␈α∀It␈α∀repeatedly␈α∪scans␈α∀a␈α∀scene␈α∪and␈α∀tries␈α∀to␈α∪name␈α∀it.␈α∀The␈α∀scene␈α∪is
␈↓ ↓H␈↓broken␈α⊗into␈α⊗a␈α∃set␈α⊗of␈α⊗features␈α⊗and␈α∃a␈α⊗set␈α⊗of␈α∃objects.␈α⊗Each␈α⊗feature␈α⊗is␈α∃a
␈↓ ↓H␈↓relation␈α⊗on␈α⊗one␈α⊗or␈α⊗more␈α∃objects␈α⊗in␈α⊗the␈α⊗scene.␈α⊗ Internally,␈α⊗the␈α∃program
␈↓ ↓H␈↓maintains␈α"a␈α"model␈α"for␈α!each␈α"differently-named␈α"concept␈α"it␈α"has␈α!ever
␈↓ ↓H␈↓encountered.␈α∩"Concept"␈α∩here␈α∩is␈α⊃used␈α∩technically,␈α∩to␈α∩indicate␈α∩a␈α⊃particular
␈↓ ↓H␈↓data␈α⊗structure␈α↔maintained␈α⊗by␈α↔the␈α⊗target␈α⊗program.␈α↔ The␈α⊗model␈α↔contains␈α⊗a
␈↓ ↓H␈↓description␈α⊃of␈α∩the␈α⊃objects␈α⊃expected␈α∩in␈α⊃the␈α⊃scene,␈α∩a␈α⊃set␈α⊃of␈α∩features␈α⊃which
␈↓ ↓H␈↓must␈α⊃be␈α⊃present␈α⊃in␈α⊃the␈α⊃scene␈α∩(else␈α⊃it␈α⊃can't␈α⊃be␈α⊃the␈α⊃same␈α⊃as␈α∩this␈α⊃concept),
␈↓ ↓H␈↓a␈α∀set␈α∀of␈α∃features␈α∀which␈α∀must␈α∀not␈α∃be␈α∀present␈α∀in␈α∀the␈α∃scene,␈α∀and␈α∀a␈α∃set␈α∀of
␈↓ ↓H␈↓features␈α~which␈α~may␈α~or␈α~may␈α~not␈α→be␈α~present.␈α~ Thus␈α~a␈α~model␈α~is␈α~like␈α→an
␈↓ ↓H␈↓archtypical␈α∪scene␈α∪plus␈α∩a␈α∪name.␈α∪ Each␈α∩time␈α∪the␈α∪program␈α∩is␈α∪confronted␈α∪by␈α∩a
␈↓ ↓H␈↓new␈α_scene,␈α_the␈α_program␈α_must␈α_scan␈α_its␈α_models␈α_until␈α_it␈α_finds␈α_one␈α_which
␈↓ ↓H␈↓matches␈α⊗it.␈α⊗A␈α∃model␈α⊗is␈α⊗said␈α⊗to␈α∃match␈α⊗a␈α⊗scene␈α∃if␈α⊗all␈α⊗the␈α⊗MUST␈α∃features
␈↓ ↓H␈↓associated␈α∪with␈α∪that␈α∩model␈α∪are␈α∪present␈α∩in␈α∪the␈α∪scene,␈α∩and␈α∪all␈α∪the␈α∩MUSTNOT
␈↓ ↓H␈↓features␈α∃are␈α∃absent␈α∃from␈α∃the␈α∀observed␈α∃scene.␈α∃The␈α∃target␈α∃program␈α∀informs
␈↓ ↓H␈↓the␈α⊂user␈α⊂of␈α⊂this␈α⊂guess,␈α⊂and␈α⊂accepts␈α⊂the␈α⊂proper␈α⊂concept␈α⊂name.␈α⊂If␈α⊂it␈α⊂guessed
␈↓ ↓H␈↓incorrectly,␈α≠it␈α≠modifies␈α≠its␈α≤models.␈α≠The␈α≠wrong␈α≠guess␈α≠model␈α≤may␈α≠have
␈↓ ↓H␈↓features␈α⊂added␈α⊂to␈α⊂its␈α⊂MUST␈α⊂or␈α⊂MUSTNOT␈α⊂sets;␈α⊂the␈α⊂correct␈α⊂concept␈α⊂name␈α⊂model
␈↓ ↓H␈↓may␈α∀have␈α∀to␈α∪be␈α∀modified␈α∀or␈α∪(if␈α∀it's␈α∀a␈α∪new␈α∀concept)␈α∀created␈α∀and␈α∪inserted
␈↓ ↓H␈↓into the list of models.  See the flowchart on page A4.7.

␈↓ ↓H␈↓For example, part of a scene might be:     OBJECTS a,b,c,d
␈↓ ↓H␈↓        (GREEN a)(BLUE c)(TOUCHES c d)(SUPPORTS a c)(SUPPORTS b c).

␈↓ ↓H␈↓A model for an arch might be:              NAME    ARCH
␈↓ ↓H␈↓                                           OBJECTS a,b,c
␈↓ ↓H␈↓        MUST    (SUPPORTS a c)(SUPPORTS b c)
␈↓ ↓H␈↓        MUSTNOT (TOUCHES a b)
␈↓ ↓H␈↓        MAY     (GREEN a)(WEDGE c)(PRISM a)(BLOCK b)(PARALLEL a b)

␈↓ ↓H␈↓Suppose␈α↔that␈α↔the␈α⊗target␈α↔program␈α↔reads␈α⊗in␈α↔the␈α↔above␈α⊗scene␈α↔and␈α↔tries␈α⊗to
␈↓ ↓H␈↓match␈α∀it␈α∃to␈α∀the␈α∀above␈α∃model␈α∀for␈α∀consistency.␈α∃ The␈α∀MUST␈α∃relations␈α∀should
␈↓ ↓H␈↓all␈α⊃be␈α∩present.␈α⊃ Yes,␈α⊃the␈α∩scene␈α⊃does␈α⊃contain␈α∩(SUPPORTS␈α⊃a␈α⊃c)␈α∩and␈α⊃(SUPPORTS
␈↓ ↓H␈↓b␈α↔c).␈α↔Next,␈α⊗the␈α↔MUSTNOT␈α↔relations␈α⊗must␈α↔be␈α↔absent␈α⊗from␈α↔the␈α↔scene.␈α⊗Sure
␈↓ ↓H␈↓enough,␈α⊂(TOUCHES␈α⊂a␈α⊂b)␈α⊂isn't␈α⊂there.␈α⊂ So␈α⊂the␈α⊂model␈α⊂and␈α⊂scene␈α⊂are␈α⊂consistent,
␈↓ ↓H␈↓and the program announces that its guess is ARCH.

␈↓ ↓H␈↓If␈α⊃the␈α⊃user␈α⊃verifies␈α∩this␈α⊃guess,␈α⊃then␈α⊃the␈α∩MAY␈α⊃set␈α⊃is␈α⊃augmented␈α∩with␈α⊃(BLUE
␈↓ ↓H␈↓c) and (TOUCHES c d), and the OBJECTS set is augmented with "d."

␈↓ ↓H␈↓If␈α∩the␈α∩user␈α∪denies␈α∩that␈α∩the␈α∪scene␈α∩is␈α∩an␈α∩arch,␈α∪the␈α∩target␈α∩program␈α∪sees␈α∩if
␈↓ ↓H␈↓there␈α∩are␈α∩any␈α∪relations␈α∩in␈α∩the␈α∪model's␈α∩MAY␈α∩set␈α∩which␈α∪do␈α∩not␈α∩occur␈α∪in␈α∩the
␈↓ ↓H␈↓scene.␈α⊃If␈α⊃so,␈α⊃one␈α∩of␈α⊃them␈α⊃(e.g.,␈α⊃(PARALLEL␈α∩a␈α⊃b))␈α⊃will␈α⊃be␈α∩transferred␈α⊃from
␈↓ ↓H␈↓the␈α∀MAY␈α∀to␈α∪the␈α∀MUST␈α∀set.␈α∪ If␈α∀no␈α∀such␈α∪feature␈α∀existed,␈α∀the␈α∀program␈α∪would
␈↓ ↓H␈↓look␈α∪for␈α∀a␈α∪feature␈α∀present␈α∪in␈α∀the␈α∪scene␈α∪but␈α∀absent␈α∪from␈α∀all␈α∪sets␈α∀of␈α∪the
␈↓ ↓H␈↓model␈α⊃(e.g.,␈α⊃(BLUE␈α⊃c)),␈α∩and␈α⊃insert␈α⊃it␈α⊃into␈α∩the␈α⊃MUSTNOT␈α⊃set.␈α⊃ Also,␈α∩if␈α⊃the
␈↓ ↓H␈↓user␈α⊂disagreed␈α⊂with␈α⊂the␈α⊂guess,␈α⊂he␈α⊂would␈α⊂be␈α⊂asked␈α⊂what␈α⊂the␈α⊂true␈α⊂name␈α⊂of␈α⊂the


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 17␈↓ 	@THEORY:  DESIGN
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓concept␈α⊃was,␈α∩and␈α⊃that␈α⊃concept's␈α∩model␈α⊃would␈α⊃have␈α∩its␈α⊃MAY␈α⊃set␈α∩augmented␈α⊃by
␈↓ ↓H␈↓any␈α∀new␈α∀features␈α∪in␈α∀the␈α∀scene.␈α∪Any␈α∀features␈α∀on␈α∪its␈α∀MUST␈α∀or␈α∀MUSTNOT␈α∪sets
␈↓ ↓H␈↓which contradicted the scene would be transferred to the MAY set.

␈↓ ↓H␈↓After␈α∪the␈α∪target␈α∪concept␈α∀formation␈α∪program␈α∪was␈α∪specified,␈α∪it␈α∀was␈α∪trimmed
␈↓ ↓H␈↓and␈α~then␈α→rewritten␈α~as␈α~a␈α→structured␈α~program␈α→[Gadwa].␈α~Next,␈α~a␈α→complete
␈↓ ↓H␈↓dialogue␈α∪was␈α∪simulated␈α∪between␈α∀the␈α∪user␈α∪and␈α∪a␈α∪human␈α∀programmer␈α∪(referred
␈↓ ↓H␈↓to␈α∃as␈α∃the␈α∃system-player)␈α∃playing␈α∀the␈α∃role␈α∃of␈α∃an␈α∃"intelligent"␈α∀automatic
␈↓ ↓H␈↓programming␈α∀system␈α∀(similar␈α∀to,␈α∀e.g.,␈α∀[Balzer]).␈α∀ The␈α∀system-player␈α∀kept
␈↓ ↓H␈↓careful␈α records␈α as␈α he␈α programmed,␈α and␈α tried␈α to␈α create␈α a␈α bug-free
␈↓ ↓H␈↓structured␈α→program.␈α→ The␈α→dialogue␈α→was␈α→then␈α→annotated:␈α→after␈α→each␈α_user
␈↓ ↓H␈↓response,␈α∩comments␈α∩were␈α∩inserted␈α⊃which␈α∩described␈α∩the␈α∩"states"␈α∩the␈α⊃system-
␈↓ ↓H␈↓player␈α∩had␈α⊃gone␈α∩through␈α∩before␈α⊃printing␈α∩his␈α⊃next␈α∩response.␈α∩ This␈α⊃included
␈↓ ↓H␈↓blind␈α↔paths␈α↔which␈α_were␈α↔tried,␈α↔use␈α↔of␈α_outside␈α↔world␈α↔knowledge,␈α_and,␈α↔in
␈↓ ↓H␈↓general,␈α⊂was␈α⊂meant␈α⊂to␈α⊂be␈α⊂the␈α⊂"intelligence"␈α⊂necessary␈α⊂to␈α⊂do␈α⊂the␈α⊂task.␈α⊂ The
␈↓ ↓H␈↓fear␈α~was␈α~that␈α~a␈α~system␈α≠could␈α~be␈α~built␈α~which␈α~synthesized␈α≠the␈α~concept
␈↓ ↓H␈↓formation␈α∪program,␈α∪and␈α∪yet␈α∀was␈α∪so␈α∪unintelligent␈α∪that␈α∪nothing␈α∀was␈α∪learned
␈↓ ↓H␈↓from it. (see section 4.1 on PW1, for example, in [Green]).

␈↓ ↓H␈↓Hopefully,␈α⊗any␈α↔system␈α⊗which␈α↔(i)␈α⊗got␈α⊗the␈α↔target␈α⊗program␈α↔correctly,␈α⊗(ii)
␈↓ ↓H␈↓followed␈α∩this␈α∩initial␈α∩dialogue,␈α⊃and,␈α∩most␈α∩importantly,␈α∩(iii)␈α∩went␈α⊃through
␈↓ ↓H␈↓the␈α∪same␈α∪line␈α∪of␈α∀reasoning␈α∪that␈α∪the␈α∪comments␈α∪indicated␈α∀the␈α∪system-player
␈↓ ↓H␈↓followed,␈α⊂would␈α⊂be␈α⊂far␈α⊂along␈α⊂the␈α⊂road␈α⊂toward␈α⊂intelligence.␈α⊂ A␈α⊂corollary␈α⊂of
␈↓ ↓H␈↓this␈α∩incremental␈α⊃annotated␈α∩protocol␈α∩approach␈α⊃is␈α∩that␈α⊃the␈α∩abilities␈α∩of␈α⊃the
␈↓ ↓H␈↓user␈α→must␈α→coincide␈α_with␈α→those␈α→of␈α→the␈α_subject␈α→who␈α→participated␈α→in␈α_the
␈↓ ↓H␈↓protocol␈α⊂(see␈α⊂also␈α⊂[Woods]).␈α⊂The␈α⊂system␈α⊂would␈α⊂be␈α⊂far␈α⊂along␈α⊂the␈α⊂road␈α⊂toward
␈↓ ↓H␈↓automatic␈α∀programming␈α∀if␈α∀it␈α∀also␈α∀(iv)␈α∀was␈α∀able␈α∀to␈α∀write␈α∀CF␈α∀from␈α∀several
␈↓ ↓H␈↓dialogues,␈α≠from␈α≠several␈α~users,␈α≠with␈α≠little␈α~preparation.␈α≠PUP6␈α≠was␈α~not
␈↓ ↓H␈↓designed␈α∃to␈α∀do␈α∃this,␈α∀and␈α∃in␈α∃the␈α∀end␈α∃it␈α∀proved␈α∃to␈α∀be␈α∃a␈α∃serious␈α∀deficit.
␈↓ ↓H␈↓Henceforth,␈α!␈↓βprotocol␈↓␈α!will␈α"refer␈α!to␈α!this␈α!user-player␈α"/␈α!system-player
␈↓ ↓H␈↓simulated dialogue.

␈↓ ↓H␈↓The␈α_target␈α_user␈α_must␈α_be␈α_familiar␈α_with␈α_LISP,␈α_well-grounded␈α_in␈α_computer
␈↓ ↓H␈↓science,␈α∩and␈α⊃have␈α∩the␈α∩input/output␈α⊃behavior␈α∩of␈α⊃the␈α∩concept␈α∩formation␈α⊃(CF)
␈↓ ↓H␈↓program␈α∃very␈α⊗clearly␈α∃in␈α∃his␈α⊗mind.␈α∃The␈α∃natural␈α⊗language␈α∃front␈α∃end␈α⊗is␈α∃so
␈↓ ↓H␈↓brittle␈α⊗that␈α⊗the␈α⊗user␈α⊗must␈α∃also␈α⊗phrase␈α⊗his␈α⊗responses␈α⊗very␈α⊗similarly␈α∃to
␈↓ ↓H␈↓those␈α∀of␈α∪the␈α∀original␈α∪protocol␈α∀subject.␈α∪ This␈α∀factor␈α∀prevented␈α∪dialogues
␈↓ ↓H␈↓from multiple users from being successful.

␈↓ ↓H␈↓At␈α≥this␈α≥point,␈α≥most␈α≥of␈α≥the␈α≥ideas␈α≥described␈α≥in␈α≥section␈α≡3␈α≥surfaced,
␈↓ ↓H␈↓including␈α⊃a␈α⊃rough␈α⊃initial␈α∩set␈α⊃of␈α⊃BEINGs.␈α⊃ Each␈α∩one␈α⊃had␈α⊃not␈α⊃much␈α∩more␈α⊃than
␈↓ ↓H␈↓a␈α↔name␈α_and␈α↔a␈α↔vague␈α_description␈α↔of␈α_what␈α↔it␈α↔must␈α_do.␈α↔ The␈α_dialogue␈α↔was
␈↓ ↓H␈↓cycled␈α∪through␈α∪again,␈α∪painstakingly,␈α∀and␈α∪the␈α∪comments␈α∪were␈α∪replaced␈α∀by␈α∪a
␈↓ ↓H␈↓description␈α∀of␈α∃which␈α∀BEINGs␈α∀would␈α∃call␈α∀which␈α∀other␈α∃BEINGs,␈α∀why,␈α∃and␈α∀the
␈↓ ↓H␈↓results␈α→of␈α→each␈α_such␈α→call.␈α→ The␈α→constraints␈α_on␈α→each␈α→BEING␈α→thus␈α_grew,
␈↓ ↓H␈↓sometimes␈α∀changed,␈α∀and␈α∀occasionally␈α∀a␈α∀new␈α∀BEING␈α∀or␈α∀BEING␈α∀part␈α∀had␈α∀to␈α∀be
␈↓ ↓H␈↓added␈α⊃to␈α∩the␈α⊃community.␈α⊃ This␈α∩process␈α⊃was␈α⊃long␈α∩(200␈α⊃hours)␈α⊃and␈α∩produced␈α⊃a


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 18␈↓ 	@THEORY:  DESIGN
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓long␈α∪(200-page)␈α∪protocol,␈α∪actually␈α∀a␈α∪hand␈α∪trace␈α∪of␈α∪the␈α∀system␈α∪execution.
␈↓ ↓H␈↓About␈α⊂eighty␈α⊂BEINGs␈α⊂were␈α⊂needed:␈α⊂a␈α⊂dozen␈α⊂domain-specific␈α⊂ones␈α⊂and␈α⊂the␈α⊂rest
␈↓ ↓H␈↓domain-independent␈α_programming␈α_knowledge.␈α_ About␈α_thirty␈α_different␈α_BEING
␈↓ ↓H␈↓parts␈α→were␈α~called␈α→for,␈α→and␈α~they␈α→are␈α→listed␈α~in␈α→Appendix␈α→1.␈α~ The␈α→next
␈↓ ↓H␈↓appendix␈α∀describes␈α∪each␈α∀BEING␈α∪briefly;␈α∀only␈α∪the␈α∀most␈α∀important␈α∪knowledge
␈↓ ↓H␈↓is mentioned.

␈↓ ↓H␈↓A␈α⊗result␈α⊗of␈α⊗this␈α⊗method␈α∃of␈α⊗incremental␈α⊗specification␈α⊗of␈α⊗BEINGs␈α⊗is␈α∃that
␈↓ ↓H␈↓each␈α⊂BEING␈α⊂has␈α⊂only␈α⊂those␈α⊂parts␈α⊂which␈α⊂are␈α⊂going␈α⊂to␈α⊂be␈α⊂used␈α⊂sometime␈α⊂during
␈↓ ↓H␈↓the␈α∪ensuing␈α∪dialogue.␈α∪This␈α∪seemed␈α∪too␈α∪specific,␈α∪so␈α∪some␈α∪effort␈α∪was␈α∩spent
␈↓ ↓H␈↓filling␈α⊗out␈α↔parts␈α⊗that␈α↔weren't␈α⊗strictly␈α⊗necessary␈α↔to␈α⊗write␈α↔the␈α⊗concept
␈↓ ↓H␈↓formation␈α∩program.␈α∩ Perhaps␈α∩more␈α⊃careful␈α∩attention␈α∩to␈α∩this␈α∩activity␈α⊃would
␈↓ ↓H␈↓have made the system more tolerant of changes in the dialogue.

␈↓ ↓H␈↓During␈α≡the␈α∨course␈α≡of␈α∨massaging␈α≡PUP6␈α≡into␈α∨writing␈α≡the␈α∨other␈α≡target
␈↓ ↓H␈↓programs,␈α∀very␈α∃few␈α∀additional␈α∀parts␈α∃had␈α∀to␈α∀be␈α∃added␈α∀to␈α∃existing␈α∀BEINGs.
␈↓ ↓H␈↓Typically,␈α∀either␈α∀an␈α∪old␈α∀part␈α∀had␈α∪to␈α∀be␈α∀generalized␈α∪or␈α∀else␈α∀a␈α∀new␈α∪BEING
␈↓ ↓H␈↓created.␈α↔After␈α↔writing␈α⊗CF,␈α↔GI,␈α↔and␈α⊗INF,␈α↔there␈α↔are␈α⊗now␈α↔an␈α↔even␈α⊗hundred
␈↓ ↓H␈↓BEINGs in PUP6.

␈↓ ↓H␈↓The␈α⊂data␈α⊂on␈α⊂how␈α⊂filled-out␈α⊂each␈α⊂BEING␈α⊂was␈α⊂--␈α⊂and␈α⊂had␈α⊂to␈α⊂be␈α⊂--␈α⊂is␈α⊂presented
␈↓ ↓H␈↓in␈α⊂several␈α⊂forms,␈α⊂here␈α⊂and␈α⊂in␈α⊂the␈α⊂appendices.␈α⊂ In␈α⊂Appendix␈α⊂1,␈α⊂next␈α⊂to␈α⊂each
␈↓ ↓H␈↓BEING␈α≠part␈α≠is␈α~the␈α≠percentage␈α≠of␈α~BEINGs␈α≠which␈α≠had␈α~to␈α≠have␈α≠this␈α~part
␈↓ ↓H␈↓specified␈α∪for␈α∪them.␈α∪Appendix␈α∪3␈α∪reveals␈α∪how␈α∪each␈α∪BEING␈α∪was␈α∪actually␈α∩used,
␈↓ ↓H␈↓including␈α∪the␈α∪number␈α∩of␈α∪its␈α∪BEING␈α∩parts␈α∪which␈α∪exist␈α∩and␈α∪were␈α∪called␈α∩upon
␈↓ ↓H␈↓during␈α∩a␈α∪dialogue.␈α∩On␈α∪the␈α∩average,␈α∪each␈α∩BEING␈α∪part␈α∩was␈α∪present␈α∩in␈α∪36%␈α∩of
␈↓ ↓H␈↓all␈α⊃BEINGs,␈α⊃and,␈α⊃also␈α⊃on␈α⊃the␈α∩average,␈α⊃each␈α⊃BEING␈α⊃had␈α⊃10.5␈α⊃of␈α⊃its␈α∩29␈α⊃parts
␈↓ ↓H␈↓specified.␈α∃This␈α⊗says␈α∃that␈α∃each␈α⊗BEING␈α∃was␈α∃actually␈α⊗asked␈α∃a␈α∃third␈α⊗of␈α∃all
␈↓ ↓H␈↓possible␈α∪questions␈α∪and␈α∩that␈α∪each␈α∪question␈α∩was␈α∪needed␈α∪in␈α∩about␈α∪a␈α∪third␈α∩of
␈↓ ↓H␈↓all␈α⊗the␈α↔BEINGs.␈α⊗ This␈α↔is␈α⊗just␈α⊗marginally␈α↔tolerable;␈α⊗if␈α↔the␈α⊗percentages
␈↓ ↓H␈↓were␈α∪much␈α∪lower,␈α∩then␈α∪the␈α∪idea␈α∩of␈α∪grouping␈α∪the␈α∩BEINGs␈α∪and␈α∪assigning␈α∩each
␈↓ ↓H␈↓group its own distinct set of questions would be clearly called for.

␈↓ ↓H␈↓The␈α⊃principle␈α∩that␈α⊃"everything␈α∩is␈α⊃BEINGs"␈α∩was␈α⊃relaxed␈α∩in␈α⊃the␈α∩interests␈α⊃of
␈↓ ↓H␈↓absolute␈α⊂CPU␈α⊂time␈α⊂and␈α⊂feasibility␈α⊂of␈α⊂coding.␈α⊂ Besides␈α⊂BEINGs,␈α⊂PUP6␈α⊂employs
␈↓ ↓H␈↓functions,␈α∀demons␈α∪and␈α∀an␈α∪assertional␈α∀data␈α∪base.␈α∀ During␈α∀the␈α∪programming,
␈↓ ↓H␈↓100␈α∃small␈α∃functions␈α∃were␈α∃written␈α∀to␈α∃supplement␈α∃the␈α∃language.␈α∃ Most␈α∀were
␈↓ ↓H␈↓typical␈α∃current␈α∀AI␈α∃language␈α∀features␈α∃[Bobrow]␈α∃(pattern-matching,␈α∀demons,
␈↓ ↓H␈↓special␈α∩data␈α∩types),␈α∩or␈α⊃tiny␈α∩additions␈α∩to␈α∩INTERLISP␈α∩[Teitelman]␈α⊃(flatten,
␈↓ ↓H␈↓set-difference),␈α⊂or␈α⊂functions␈α⊂which␈α⊂manage␈α⊂BEINGs␈α⊂(add-a-new-being,␈α⊂print-
␈↓ ↓H␈↓a-being's-parts).␈α⊂ Many␈α⊂of␈α⊂these␈α⊂features␈α⊂were␈α⊂simplified␈α⊂(and␈α⊂speeded␈α⊂up)
␈↓ ↓H␈↓by␈α⊂using␈α⊂the␈α⊂knowledge␈α⊂that␈α⊂PUP6␈α⊂was␈α⊂to␈α⊂be␈α⊂an␈α⊂AP␈α⊂system.␈α⊂ For␈α⊂example,␈α⊂all
␈↓ ↓H␈↓the␈α∃different␈α⊗types␈α∃of␈α∃assertions␈α⊗that␈α∃an␈α∃AP␈α⊗system␈α∃might␈α∃want␈α⊗to␈α∃make
␈↓ ↓H␈↓deal␈α⊃with␈α∩different␈α⊃concerns␈α∩of␈α⊃programming.␈α∩ Thus␈α⊃a␈α∩group␈α⊃of␈α∩about␈α⊃forty
␈↓ ↓H␈↓different␈α⊗assertion␈α↔patterns␈α⊗could␈α↔be␈α⊗fixed,␈α⊗each␈α↔one␈α⊗becoming␈α↔a␈α⊗named
␈↓ ↓H␈↓list;␈α$this␈α$almost␈α$eliminated␈α$searching␈α$during␈α$retrieval␈α$from␈α$the
␈↓ ↓H␈↓assertional base.


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 19␈↓ 	@THEORY:  DESIGN
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓␈↓↓6.  REALITY: EXAMPLES␈↓

␈↓ ↓H␈↓An␈α≤example␈α≠of␈α≤the␈α≤PUP6␈α≠community␈α≤of␈α≤BEINGs␈α≠interacting␈α≤will␈α≤now␈α≠be
␈↓ ↓H␈↓presented.␈α⊃Let's␈α∩jump␈α⊃one␈α⊃third␈α∩of␈α⊃the␈α⊃way␈α∩into␈α⊃the␈α⊃dialogue␈α∩which␈α⊃writes
␈↓ ↓H␈↓CF.␈α≥The␈α≥system␈α≥learns␈α≥it␈α≥must␈α≥compare␈α≥the␈α≥input␈α≥scene␈α≡against␈α≥its
␈↓ ↓H␈↓internally␈α⊗stored␈α↔models␈α⊗of␈α↔concepts,␈α⊗until␈α⊗it␈α↔finds␈α⊗one␈α↔which␈α⊗doesn't
␈↓ ↓H␈↓fail␈α∩the␈α∩comparison.␈α∪ It␈α∩asks␈α∩the␈α∪user␈α∩what␈α∩it␈α∩means␈α∪for␈α∩scene␈α∩S␈α∪to␈α∩fail
␈↓ ↓H␈↓the␈α∀comparison␈α∃to␈α∀model␈α∀M.␈α∃The␈α∀user␈α∀replies,␈α∃whenever␈α∀M␈α∃is␈α∀incompatible
␈↓ ↓H␈↓with␈α∪the␈α∪observed␈α∩features␈α∪of␈α∪S.␈α∩ The␈α∪IDEN␈α∪part␈α∩of␈α∪the␈α∪CONTRADICTS␈α∩BEING
␈↓ ↓H␈↓recognizes this sentence pattern, and transforms it to
␈↓ ↓H␈↓(FORSOME  F  IN M_FEATURES (specialized:contradicts F S_FEATURES)).

␈↓ ↓H␈↓The␈α∪BEING␈α∪which␈α∪inserts␈α∪this␈α∪into␈α∪the␈α∪synthesized␈α∪code␈α∪requires␈α∪that␈α∩the
␈↓ ↓H␈↓user␈α∩pick␈α∩some␈α∩proper␈α⊃name␈α∩for␈α∩the␈α∩function␈α∩specialized:contradicts;␈α⊃this
␈↓ ↓H␈↓will␈α⊂be␈α⊂a␈α⊂streamlined␈α⊂contradiction␈α⊂test␈α⊂written␈α⊂by␈α⊂the␈α⊂CONTRADICTS␈α⊂BEING.
␈↓ ↓H␈↓Say␈α⊂the␈α⊂user␈α⊂reponds␈α⊂by␈α⊂calling␈α⊂it␈α⊂IMPOSS.␈α⊂This␈α⊂naming␈α⊂and␈α⊂specializing␈α⊂is
␈↓ ↓H␈↓central␈α∪to␈α∪BEING␈α∪creation:␈α∪a␈α∪BEING␈α∪recognizes␈α∪an␈α∪instance␈α∪of␈α∪itself,␈α∩and
␈↓ ↓H␈↓decides␈α∪either␈α∪to␈α∪insert␈α∀a␈α∪call␈α∪to␈α∪itself␈α∪or␈α∀else␈α∪to␈α∪insert␈α∪a␈α∪call␈α∀to␈α∪a
␈↓ ↓H␈↓specialized␈α∩version␈α⊃of␈α∩itself.␈α∩ If␈α⊃any␈α∩nontrivial␈α⊃decisions␈α∩must␈α∩be␈α⊃made,
␈↓ ↓H␈↓and␈α→can␈α→be␈α_settled␈α→at␈α→synthesis␈α→time,␈α_then␈α→the␈α→latter␈α→alternative␈α_is
␈↓ ↓H␈↓chosen.␈α⊂ CONTRADICTS␈α⊂is␈α⊂too␈α⊂general␈α⊂a␈α⊂BEING␈α⊂to␈α⊂be␈α⊂called␈α⊂in␈α⊂an␈α⊂inner␈α⊂loop,
␈↓ ↓H␈↓so␈α⊃its␈α⊃content␈α⊃will␈α∩be␈α⊃hammered␈α⊃out␈α⊃at␈α∩synthesis␈α⊃time.␈α⊃On␈α⊃the␈α∩other␈α⊃hand,
␈↓ ↓H␈↓FORSOME␈α→is␈α→so␈α_primitive␈α→that␈α→no␈α→specialized␈α_version␈α→of␈α→it␈α→is␈α_written
␈↓ ↓H␈↓normally.

␈↓ ↓H␈↓Here␈α∪is␈α∪the␈α∩way␈α∪this␈α∪piece␈α∩of␈α∪the␈α∪dialogue␈α∩actually␈α∪appears.␈α∪ The␈α∩user's
␈↓ ↓H␈↓reponses␈α∀are␈α∀italicised.␈α∀ The␈α∀system␈α∀informs␈α∀the␈α∀user␈α∀of␈α∀where␈α∀it␈α∀is␈α∀by
␈↓ ↓H␈↓simulating␈α~a␈α~cursor␈α~pointing␈α~into␈α≠a␈α~graph␈α~of␈α~program␈α~code.␈α≠ This␈α~is
␈↓ ↓H␈↓analogous to the textual and dynamic indices which [Dijkstra] suggests.

␈↓ ↓H␈↓PLEASE TYPE IN A LOGICAL EXPRESSION WHICH IS TRUE WHEN WE TERMINATE
␈↓ ↓H␈↓       THE LOOP, AND IS FALSE OTHERWISE.

␈↓ ↓H␈↓SHOULD I DISCUSS RAMIFICATIONS?␈↓βNO␈↓

␈↓ ↓H␈↓USER: ␈↓β(ANY FEATURE IN MODEL:FEATURES IS INCOMPATIBLE
␈↓ ↓H␈↓β    WITH SCENE:FEATURES)␈↓

␈↓ ↓H␈↓PUP WANTS USER TO TYPE IN NAME FOR  SPECIALIZED VERSION OF CONTRADICTS.

␈↓ ↓H␈↓USER: ␈↓βIMPOSS␈↓

␈↓ ↓H␈↓Later␈α∀in␈α∃the␈α∀dialogue,␈α∀PUP6␈α∃decides␈α∀it␈α∀must␈α∃expand␈α∀the␈α∃function␈α∀IMPOSS.
␈↓ ↓H␈↓The␈α∃CONTRADICTS␈α∃BEING␈α∃is␈α∃again␈α∃called␈α∃on;␈α∃this␈α∃time␈α∃it␈α∃is␈α∃asked␈α∃how␈α∀to
␈↓ ↓H␈↓write␈α_a␈α_specialized␈α_version␈α_of␈α_a␈α_contradiction␈α_test.␈α_ It␈α_replies␈α_that
␈↓ ↓H␈↓SOME_OF␈α_the␈α_following␈α_types␈α_of␈α_contradiction␈α_may␈α_occur:␈α_PROBABILITY:0,
␈↓ ↓H␈↓PROBABILITY:1,␈α∪and␈α∪PROBABILITY:ε(0,1).␈α∪ This␈α∀is␈α∪the␈α∪germ␈α∪of␈α∪the␈α∀idea␈α∪for


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 20␈↓ 	 REALITY:  EXAMPLES
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓the␈α∀MUSTNOT/MUST/MAY␈α∀categorization␈α∀of␈α∀features.␈α∀The␈α∀SOME_OF␈α∀BEING␈α∀takes
␈↓ ↓H␈↓control,␈α⊗and␈α⊗asks␈α⊗if␈α⊗the␈α∃decision␈α⊗can␈α⊗be␈α⊗deferred.␈α⊗ The␈α⊗DEFERRAL␈α∃BEING
␈↓ ↓H␈↓looks␈α⊃about,␈α⊃first␈α⊃asking␈α∩if␈α⊃there␈α⊃is␈α⊃any␈α∩non-null␈α⊃piece␈α⊃of␈α⊃code␈α∩that␈α⊃all
␈↓ ↓H␈↓three␈α~have␈α→in␈α~common.␈α~ This␈α→fails,␈α~and␈α→eventually␈α~the␈α~DEFERRAL␈α→BEING
␈↓ ↓H␈↓reports␈α⊂failure.␈α⊂ SOME_OF␈α⊂sees␈α⊂it␈α⊂has␈α⊂no␈α⊂basis␈α⊂upon␈α⊂which␈α⊂to␈α⊂form␈α⊂a␈α⊂guess,
␈↓ ↓H␈↓and␈α∀wants␈α∀somebody␈α∀to␈α∀ask␈α∀the␈α∀user.␈α∀ The␈α∀ASK_USER␈α∀BEING␈α∀takes␈α∀over,␈α∀and
␈↓ ↓H␈↓trivially␈α↔finds␈α↔out␈α⊗what␈α↔exactly␈α↔it␈α⊗is␈α↔that␈α↔PUP6␈α⊗wants␈α↔to␈α↔learn.␈α⊗ The
␈↓ ↓H␈↓names␈α∀of␈α∀the␈α∪three␈α∀choices␈α∀are␈α∪so␈α∀cryptic␈α∀that␈α∪their␈α∀WHAT␈α∀and␈α∀HOW␈α∪parts
␈↓ ↓H␈↓are␈α⊃printed␈α⊃out␈α⊃to␈α⊃the␈α⊃user,␈α∩as␈α⊃well␈α⊃as␈α⊃their␈α⊃names.␈α⊃ The␈α⊃user␈α∩types␈α⊃back
␈↓ ↓H␈↓his␈α∪choices,␈α∪in␈α∪our␈α∪case␈α∪all␈α∪three.␈α∪ SOME_OF␈α∪composes␈α∪three␈α∪new␈α∩function
␈↓ ↓H␈↓calls, separated by a conditional:

␈↓ ↓H␈↓(COND ( (IS_OF_TYPE         F   PROBABILITY:0_PART_OF_M_FEATURES)
␈↓ ↓H␈↓        (PROBABILITY:0_CONTRADICTION    F    S_FEATURES))
␈↓ ↓H␈↓      ( (IS_OF_TYPE         F   PROBABILITY:1_PART_OF_M_FEATURES)
␈↓ ↓H␈↓        (PROBABILITY:1_CONTRADICTION    F    S_FEATURES))
␈↓ ↓H␈↓      ( (IS_OF_TYPE         F   PROBABILITYε(0,1)_PART_OF_M_FEATURES)
␈↓ ↓H␈↓        (PROBABILITYε(0,1)_CONTRADICTION  F  S_FEATURES)))

␈↓ ↓H␈↓TRICHOTOMY␈α⊂recognizes␈α⊂this␈α⊂as␈α⊂a␈α⊂split␈α⊂on␈α⊂a␈α⊂function's␈α⊂values␈α⊂being␈α⊂=0,␈α⊂=1,
␈↓ ↓H␈↓or␈α⊗between␈α⊗zero␈α⊗and␈α⊗one.␈α∃ It␈α⊗asks␈α⊗whether␈α⊗this␈α⊗particular␈α⊗function␈α∃can
␈↓ ↓H␈↓only␈α⊂range␈α⊂over␈α⊂the␈α⊂interval␈α⊂[0,1].␈α⊂ PROBABILITY␈α⊂answers␈α⊂affirmatively,␈α⊂so
␈↓ ↓H␈↓SOME_OF␈α∪replaces␈α∪the␈α∪final␈α∪IS_OF_TYPE␈α∪test␈α∪by␈α∪the␈α∪constant␈α∪T.␈α∪ Later␈α∩on,
␈↓ ↓H␈↓PUP6␈α!must␈α"worry␈α!about␈α"the␈α!other␈α"two␈α!tests,␈α"and␈α!about␈α"the␈α!three
␈↓ ↓H␈↓contradiction␈α→predicates.␈α→ These␈α→latter␈α→entities␈α→know␈α~(their␈α→ENCODABLE
␈↓ ↓H␈↓parts␈α→tell␈α→them)␈α→that␈α→they␈α→are␈α→immediately␈α→encodable.␈α→A␈α_probability=0
␈↓ ↓H␈↓contradiction␈α↔means␈α↔that␈α⊗arg1␈α↔must␈α↔not␈α⊗occur␈α↔in␈α↔the␈α⊗world␈α↔arg2␈α↔yet␈α⊗it
␈↓ ↓H␈↓does.␈α≡ So␈α≡the␈α≡META-CODE␈α≡of␈α≡the␈α≡PROBABILITY:0_CONTRADICTION␈α≡BEING␈α≡is
␈↓ ↓H␈↓defined␈α∀as␈α∃(MEMBER␈α∀arg1␈α∀arg2).␈α∃ This␈α∀corresponds␈α∀to␈α∃a␈α∀MUSTNOT␈α∃feature␈α∀F
␈↓ ↓H␈↓which␈α∩is␈α∩present␈α∪in␈α∩the␈α∩world␈α∪(in␈α∩the␈α∩set␈α∩of␈α∪S_FEATURES␈α∩of␈α∩the␈α∪scene.)␈α∩A
␈↓ ↓H␈↓probability=1␈α∪contradiction␈α∪occurs␈α∪when␈α∀a␈α∪feature␈α∪arg1␈α∪must␈α∪occur␈α∀in␈α∪the
␈↓ ↓H␈↓world␈α⊃arg2,␈α∩yet␈α⊃it␈α⊃doesn't.␈α∩So␈α⊃its␈α⊃definition␈α∩is␈α⊃simply␈α⊃(NOT␈α∩(MEMBER␈α⊃arg1
␈↓ ↓H␈↓arg2)).␈α⊂ It␈α⊂is␈α⊂impossible␈α⊂for␈α⊂a␈α⊂feature␈α⊂with␈α⊂probability␈α⊂in␈α⊂(0,1)␈α⊂to␈α⊂be␈α⊂in
␈↓ ↓H␈↓contradiction␈α↔with␈α↔any␈α↔world␈α↔(lacking␈α↔negated␈α↔features),␈α↔so␈α_this␈α↔third
␈↓ ↓H␈↓predicate␈α⊃is␈α⊃defined␈α⊃as␈α⊃the␈α⊃constant␈α∩NIL.␈α⊃ That␈α⊃is,␈α⊃if␈α⊃F␈α⊃is␈α⊃a␈α∩MAY␈α⊃feature
␈↓ ↓H␈↓of␈α_the␈α↔model␈α_M,␈α_then␈α↔there␈α_can␈α↔be␈α_no␈α_contradiction␈α↔between␈α_F␈α_and␈α↔␈↓βany␈↓
␈↓ ↓H␈↓features of the scene S.

␈↓ ↓H␈↓When␈α↔a␈α↔BEING␈α↔is␈α↔said␈α↔to␈α↔do␈α⊗or␈α↔recognize␈α↔or␈α↔know␈α↔something,␈α↔as␈α↔in␈α⊗the
␈↓ ↓H␈↓preceding␈α⊃and␈α∩following␈α⊃paragraphs,␈α∩what␈α⊃is␈α∩actually␈α⊃meant␈α∩is␈α⊃that␈α∩one␈α⊃or
␈↓ ↓H␈↓more␈α⊃of␈α∩its␈α⊃parts␈α⊃specificly␈α∩encode␈α⊃that␈α⊃knowledge.␈α∩ All␈α⊃the␈α⊃parts␈α∩of␈α⊃the
␈↓ ↓H␈↓hundred␈α∩BEINGs␈α∪in␈α∩PUP6␈α∪were␈α∩coded␈α∪by␈α∩hand,␈α∪not␈α∩by␈α∪each␈α∩other.␈α∪ They␈α∩then
␈↓ ↓H␈↓can encode other BEINGs, interacting only via the dialogue.

␈↓ ↓H␈↓The␈α⊃IS_OF_TYPE␈α∩BEING␈α⊃recognizes␈α⊃that␈α∩it␈α⊃must␈α⊃work␈α∩hard␈α⊃to␈α⊃replace␈α∩each␈α⊃of
␈↓ ↓H␈↓the␈α∩two␈α⊃case␈α∩tests,␈α∩unless␈α⊃M_FEATURES␈α∩is␈α⊃organized␈α∩permanently␈α∩into␈α⊃three
␈↓ ↓H␈↓parts␈α⊂(thus␈α⊂permitting␈α⊂the␈α⊂complex␈α⊂function␈α⊂"IS_OF_TYPE"␈α⊂to␈α⊂be␈α⊂replaced␈α⊂by


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 21␈↓ 	 REALITY:  EXAMPLES
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓the␈α-simple␈α-one␈α-"MEMBER"␈α-in␈α,the␈α-above␈α-piece␈α-of␈α-code).␈α,The
␈↓ ↓H␈↓STRUCTURE_INDUCING␈α∀BEING␈α∪will␈α∀take␈α∪over,␈α∀to␈α∪probe␈α∀the␈α∀permissability␈α∪and
␈↓ ↓H␈↓the␈α≡difficulty␈α∨of␈α≡such␈α∨a␈α≡constraint.␈α≡ It␈α∨finds␈α≡nothing␈α∨about␈α≡this
␈↓ ↓H␈↓tripartite␈α⊗structuring␈α⊗which␈α⊗could␈α⊗damage␈α⊗any␈α⊗earlier␈α⊗synthesized␈α⊗code,
␈↓ ↓H␈↓and␈α_asks␈α_the␈α_user's␈α_blessing.␈α_ Notes␈α_are␈α_added␈α_to␈α_the␈α_list␈α_of␈α_coding
␈↓ ↓H␈↓warnings,␈α⊂stating␈α⊂that␈α⊂any␈α⊂reference␈α⊂to␈α⊂the␈α⊂entire␈α⊂list␈α⊂of␈α⊂M_FEATURES␈α⊂must
␈↓ ↓H␈↓be␈α⊗replaced␈α⊗by␈α⊗either␈α⊗APPEND␈α⊗of␈α↔the␈α⊗three␈α⊗new␈α⊗lists,␈α⊗or␈α⊗else␈α↔by␈α⊗three
␈↓ ↓H␈↓separate␈α∃statements.␈α∃GET_NAME␈α∃is␈α∃indirectly␈α∀called,␈α∃and␈α∃he␈α∃has␈α∃the␈α∀user
␈↓ ↓H␈↓name␈α_the␈α_three␈α_new␈α_sets␈α_of␈α_features;␈α_say␈α_he␈α_responds␈α_by␈α_calling␈α_them
␈↓ ↓H␈↓MUSTNOT,␈α⊗MUST,␈α⊗and␈α⊗MAY.␈α⊗The␈α⊗system␈α↔would␈α⊗at␈α⊗this␈α⊗point␈α⊗say␈α⊗to␈α↔draw␈α⊗an
␈↓ ↓H␈↓arrow␈α∪on␈α∪its␈α∩graph␈α∪of␈α∪code,␈α∩from␈α∪the␈α∪function␈α∩call␈α∪(IMPOSS␈α∪F␈α∩S_FEATURES)
␈↓ ↓H␈↓to the new block of code:

␈↓ ↓H␈↓  (COND ( (MEMBER        F   MUSTNOT_PART_OF_M)
␈↓ ↓H␈↓          (MEMBER        F   S_FEATURES))
␈↓ ↓H␈↓        ( (MEMBER        F   MUST_PART_OF_M)
␈↓ ↓H␈↓          (NOT (MEMBER   F   S_FEATURES))
␈↓ ↓H␈↓        (  T (COMMENT THIS "T" REPLACES "MEMBER F MAY_PART_OF_M")
␈↓ ↓H␈↓           NIL))

␈↓ ↓H␈↓This␈α∀is␈α∀now␈α∪the␈α∀META:CODE␈α∀part␈α∪of␈α∀the␈α∀new␈α∪BEING␈α∀called␈α∀IMPOSS.␈α∀ Most␈α∪of
␈↓ ↓H␈↓the␈α↔other␈α↔parts␈α↔are␈α↔taken␈α↔from␈α↔its␈α↔generalization,␈α_namely␈α↔CONTRADICTS.
␈↓ ↓H␈↓During␈α↔the␈α↔course␈α_of␈α↔writing␈α↔this␈α↔piece,␈α_however,␈α↔some␈α↔of␈α_these␈α↔parts
␈↓ ↓H␈↓would␈α∪be␈α∪slightly␈α∪changed.␈α∪For␈α∪example,␈α∪its␈α∪reason␈α∪for␈α∪existing␈α∪would␈α∩be
␈↓ ↓H␈↓strengthened␈α≠when␈α≠the␈α~simple␈α≠MEMBER␈α≠function␈α~calls␈α≠replaced␈α≠the␈α~slow
␈↓ ↓H␈↓IS_OF_TYPE␈α⊂BEING␈α⊂calls.␈α⊂ Here␈α⊂is␈α⊂the␈α⊂actual␈α⊂transcript␈α⊂of␈α⊂this␈α⊂part␈α⊂of␈α⊂the
␈↓ ↓H␈↓dialogue;␈α∃it␈α⊗may␈α∃also␈α∃be␈α⊗seen␈α∃(with␈α∃the␈α⊗names␈α∃slightly␈α∃changed)␈α⊗in␈α∃the
␈↓ ↓H␈↓appendix, on pages A5.10 to A5.12.

␈↓ ↓H␈↓MOVE CURSOR TO  IMPOSS TYPE OF   CONTRADICTS

␈↓ ↓H␈↓SORRY TO BOTHER YOU, BUT I CAN NO LONGER DEFER THIS SOMEOF DECISION
␈↓ ↓H␈↓    (PROBABILITY=1:CONTRADICTION PROBABILITY=0:CONTRADICTION
␈↓ ↓H␈↓        PROBABILITY>0&<1:CONTRADICTION)
␈↓ ↓H␈↓SINCE THE DECISION IS SOME:OF, TYPE ANY ORDERED SUBSET OF:
␈↓ ↓H␈↓  (A .... PROBABILITY=1:CONTRADICTION)
␈↓ ↓H␈↓  (B .... PROBABILITY=0:CONTRADICTION)
␈↓ ↓H␈↓  (C .... PROBABILITY>0&<1:CONTRADICTION)

␈↓ ↓H␈↓<discussion of the ramifications of each of these types of contradiction>

␈↓ ↓H␈↓USER: ␈↓β(A B C)␈↓

␈↓ ↓H␈↓(I RECOMMEND THAT MODEL:FEATURES BE STRUCTURED INTO (AT
␈↓ ↓H␈↓    LEAST ALONG ONE DIMENSION) THESE 3 PIECES:
␈↓ ↓H␈↓(PROBABILITY=1:CONTRADICTION:PART:OF:MODEL:FEATURES
␈↓ ↓H␈↓ PROBABILITY=0:CONTRADICTION:PART:OF:MODEL:FEATURES
␈↓ ↓H␈↓ PROBABILITY>0&<1:CONTRADICTION:PART:OF:MODEL:FEATURES).

␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 22␈↓ 	 REALITY:  EXAMPLES
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓PLEASE TYPE BACK YES, NO, OR UNSURE.)

␈↓ ↓H␈↓USER: ␈↓βYES␈↓

␈↓ ↓H␈↓PUP WANTS USER TO TYPE IN A SHORTER NAME FOR
␈↓ ↓H␈↓  ( PROBABILITY:1:CONTRADICTION:PART:OF:MODEL:FEATURES)
␈↓ ↓H␈↓USER: ␈↓βMUST:FEATURES␈↓
␈↓ ↓H␈↓ .
␈↓ ↓H␈↓ .
␈↓ ↓H␈↓ .
␈↓ ↓H␈↓DRAW A LINE FROM THE FUNCTION CALL  (IMPOSS FEATURE SCENE:FEATURES)
␈↓ ↓H␈↓          OF THE FUNCTION IMPOSS TO THIS NEW PIECE OF CODE, WHICH
␈↓ ↓H␈↓    IS ITS BODY:

␈↓ ↓H␈↓(IMPOSS
␈↓ ↓H␈↓  (LAMBDA (ARG1 ARG2)
␈↓ ↓H␈↓    (COMMENT IN ALL CALLS TO DATE, ARG1 IS INSTANTIATED AS FEATURE
␈↓ ↓H␈↓      AND ARG2 IS INSTANTIATED AS SCENE:FEATURES)
␈↓ ↓H␈↓    (COND
␈↓ ↓H␈↓      ((MEMBER ARG1 MUST:FEATURES)
␈↓ ↓H␈↓        (COMMENT ARG1 OCCURS WITH PROBABILITY 1, SO IT HAD BETTER BE
␈↓ ↓H␈↓                         IN ARG2, THE RELEVANT PIECE OF THE WORLD)
␈↓ ↓H␈↓        (NOT (MEMBER ARG1 ARG2))))
␈↓ ↓H␈↓      ((MEMBER ARG1 MUSTNOT:FEATURES)
␈↓ ↓H␈↓        (COMMENT SINCE ARG1 SHOULD NEVER OCCUR, WE HAVE A
␈↓ ↓H␈↓                CONTRADICTION IF IT IS A MEMBER OF ARG2)
␈↓ ↓H␈↓        (MEMBER ARG1 ARG2)))
␈↓ ↓H␈↓      (T (COMMENT WE MAY OR MAY NOT HAVE ARG1 IN ARG2; EITHER
␈↓ ↓H␈↓                       CASE IS ALLOWABLE; SO WE
␈↓ ↓H␈↓                       NEVER HAVE A CONTRADICTION)
␈↓ ↓H␈↓        NIL))))

␈↓ ↓H␈↓IMPOSS  has now been redefined as a BEING.

␈↓ ↓H␈↓(IN ALL CODE GENERATED,
␈↓ ↓H␈↓    ALL OCCURRENCES OF MODEL:FEATURES HAVE BEEN REPLACED
␈↓ ↓H␈↓    BY   (APPEND MUST:FEATURES MUSTNOT:FEATURES MAY:FEATURES))


␈↓ ↓H␈↓Notice␈α∩that␈α∪only␈α∩a␈α∪few␈α∩messages␈α∪have␈α∩passed␈α∪from␈α∩user␈α∪to␈α∩PUP6␈α∪during␈α∩all
␈↓ ↓H␈↓this␈α$processing.␈α# The␈α$user␈α#has␈α$the␈α#feeling␈α$of␈α$merely␈α#directing,
␈↓ ↓H␈↓constraining,␈α&and␈α&watching␈α&the␈α&activities␈α&of␈α&a␈α&busy␈α&programmer.
␈↓ ↓H␈↓Unfortunately,␈α∃"the␈α∃user"␈α∃is␈α∃not␈α∀generic;␈α∃there␈α∃was␈α∃only␈α∃one␈α∀successful
␈↓ ↓H␈↓user.␈α"As␈α"was␈α"mentioned␈α!earlier,␈α"PUP6␈α"insists␈α"on␈α"doing␈α!structured
␈↓ ↓H␈↓programming,␈α∀so␈α∪its␈α∀traces␈α∪are␈α∀superficially␈α∪similar␈α∀to␈α∀macro␈α∪expansion.
␈↓ ↓H␈↓Despite␈α∃this␈α∃concentration␈α∃on␈α∃planning,␈α∀no␈α∃BEINGs␈α∃system␈α∃should␈α∃halt␈α∀so
␈↓ ↓H␈↓long as any details remain.


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 23␈↓ 	 REALITY:  EXAMPLES
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓␈↓↓7. REALITY: RESULTS␈↓

␈↓ ↓H␈↓The␈α≥nature␈α≡of␈α≥the␈α≥task␈α≡is␈α≥of␈α≥course␈α≡central␈α≥to␈α≥any␈α≡discussion␈α≥of
␈↓ ↓H␈↓performance.␈α∩ For␈α⊃that␈α∩reason,␈α∩this␈α⊃section␈α∩will␈α⊃deal␈α∩more␈α∩with␈α⊃automatic
␈↓ ↓H␈↓programming␈α⊂than␈α⊂with␈α⊂representing␈α⊂knowledge.␈α⊂ The␈α⊂success␈α⊂of␈α⊂an␈α⊂AI␈α⊂effort
␈↓ ↓H␈↓can␈α∩be␈α⊃assessed␈α∩only␈α∩where␈α⊃accepted␈α∩standards␈α⊃of␈α∩intelligence␈α∩exist.␈α⊃ The
␈↓ ↓H␈↓character␈α∪of␈α∪the␈α∩dialogue␈α∪(described␈α∪in␈α∩Section␈α∪6␈α∪and␈α∩in␈α∪Appendix␈α∪5)␈α∩is,
␈↓ ↓H␈↓of␈α⊂course,␈α⊂one␈α⊂important␈α⊂measure␈α⊂of␈α⊂the␈α⊂intelligence␈α⊂of␈α⊂an␈α⊂AP␈α⊂system.␈α⊂ One
␈↓ ↓H␈↓which␈α⊂asked␈α⊂"What␈α⊂is␈α⊂the␈α⊂first␈α⊂instruction?␈α⊂ What␈α⊂is␈α⊂the␈α⊂second...?"␈α⊂would
␈↓ ↓H␈↓be␈α⊗universal␈α⊗but␈α⊗worse␈α⊗than␈α∃useless.␈α⊗In␈α⊗this␈α⊗section␈α⊗are␈α⊗some␈α∃proposed
␈↓ ↓H␈↓questions␈α≥one␈α≥should␈α≥ask␈α≥when␈α≥confronted␈α≥by␈α≥a␈α≥new␈α≥AP␈α≡system␈α≥which
␈↓ ↓H␈↓generates␈α∀code␈α∪heuristically␈α∀from␈α∪a␈α∀dialogue.␈α∪ The␈α∀answers␈α∀pertaining␈α∪to
␈↓ ↓H␈↓PUP6␈α→are␈α→parenthesized␈α→after␈α→each␈α→question.␈α→ Only␈α→capsules␈α→are␈α_given;
␈↓ ↓H␈↓fuller answers are located elsewhere.

␈↓ ↓H␈↓The␈α⊂questions␈α⊂break␈α⊂into␈α⊂two␈α⊂categories.␈α⊂First,␈α⊂one␈α⊂wants␈α⊂to␈α⊂know␈α⊂what␈α⊂the
␈↓ ↓H␈↓system␈α⊃does.␈α∩ Most␈α⊃important,␈α⊃does␈α∩it␈α⊃write␈α⊃a␈α∩program?␈α⊃ (yes.)␈α⊃If␈α∩so,␈α⊃how
␈↓ ↓H␈↓complex␈α→is␈α→that␈α_task,␈α→and␈α→what␈α→is␈α_the␈α→program␈α→specification␈α→like?␈α_(a
␈↓ ↓H␈↓concept␈α∩formation␈α∩program,␈α∩several␈α⊃pages␈α∩long,␈α∩from␈α∩one␈α∩specific␈α⊃protocol
␈↓ ↓H␈↓dialogue).␈α∀ How␈α∀precise␈α∀must␈α∀the␈α∀user␈α∀be:␈α∀may␈α∀he␈α∀err␈α∀(no),␈α∀forget␈α∀(no),
␈↓ ↓H␈↓change␈α∪his␈α∪mind?␈α∪(yes,␈α∪in␈α∪limited␈α∪cases.)␈α∪How␈α∪detailed␈α∪must␈α∪his␈α∩dialogue
␈↓ ↓H␈↓be?␈α⊂(by␈α⊂construction,␈α⊂just␈α⊂about␈α⊂as␈α⊂detailed␈α⊂as␈α⊂if␈α⊂he␈α⊂were␈α⊂talking␈α⊂to␈α⊂a␈α⊂CS
␈↓ ↓H␈↓grad␈α→student␈α→programmer.)␈α→How␈α→closely␈α→does␈α→the␈α→dialogue␈α→determine␈α_the
␈↓ ↓H␈↓details␈α≥of␈α≥the␈α≥final␈α≥code?␈α≤ (some␈α≥inferences␈α≥are␈α≥made,␈α≥and␈α≤several
␈↓ ↓H␈↓representational␈α⊂choices,␈α⊂but␈α⊂much␈α⊂of␈α⊂the␈α⊂final␈α⊂code␈α⊂is␈α⊂clearly␈α⊂determined
␈↓ ↓H␈↓by␈α⊃the␈α⊃precise␈α⊃user␈α∩responses.)␈α⊃How␈α⊃does␈α⊃the␈α∩user␈α⊃know␈α⊃where␈α⊃he␈α∩is␈α⊃during
␈↓ ↓H␈↓the␈α"dialogue?␈α"(simulated␈α"cursors␈α"pointing␈α"to␈α"a␈α"graph␈α"representing
␈↓ ↓H␈↓synthesized code.)

␈↓ ↓H␈↓Quite␈α_seriously,␈α_an␈α_important␈α_question␈α_is␈α_whether␈α_the␈α_system␈α_writes␈α_a
␈↓ ↓H␈↓second␈α≤program.␈α≤(yes.)␈α≤If␈α≤so,␈α≤how␈α≤does␈α≤it␈α≤relate␈α≤to␈α≤the␈α≤first␈α≤one
␈↓ ↓H␈↓synthesized?␈α⊂(both␈α⊂are␈α⊂inductive␈α⊂inference␈α⊂LISP␈α⊂programs.)␈α⊂How␈α⊂much␈α⊂of␈α⊂the
␈↓ ↓H␈↓AP␈α⊗system␈α⊗is␈α↔actually␈α⊗used␈α⊗in␈α⊗writing␈α↔␈↓βboth␈↓␈α⊗programs?␈α⊗(49␈α⊗BEINGs␈α↔out␈α⊗of
␈↓ ↓H␈↓79.)␈α∀One␈α∀should␈α∪ask␈α∀what␈α∀the␈α∪full␈α∀range␈α∀of␈α∪programs␈α∀is␈α∀which␈α∀the␈α∪system
␈↓ ↓H␈↓has␈α"successfully␈α"synthesized.␈α#(the␈α"concept␈α"former,␈α#the␈α"grammatical
␈↓ ↓H␈↓inferrer,␈α≡and␈α≡the␈α≡simple␈α≡information␈α≡manipulation␈α≡system.)␈α≡The␈α≡dual
␈↓ ↓H␈↓questions␈α∪to␈α∪these␈α∪inquire␈α∪whether␈α∪a␈α∪program␈α∪may␈α∪be␈α∪generated␈α∪by␈α∩several
␈↓ ↓H␈↓different␈α∪(in␈α∪the␈α∩sense␈α∪of␈α∪rephrasing␈α∩and␈α∪in␈α∪the␈α∩sense␈α∪of␈α∪reordering␈α∩the
␈↓ ↓H␈↓subtasks)␈α_dialogues␈α_(theoretically,␈α_but␈α_not␈α_practically),␈α_and␈α_what␈α_the
␈↓ ↓H␈↓range␈α≤of␈α≤variability␈α≤is.␈α≤(theoretically␈α≤large,␈α≤but␈α≤practically␈α≤quite
␈↓ ↓H␈↓limited.)␈α∃Similarly,␈α∃what␈α∃about␈α∃the␈α∀target␈α∃language:␈α∃is␈α∃it␈α∃a␈α∀parameter?
␈↓ ↓H␈↓(no,␈α∀always␈α∀the␈α∪same.)␈α∀How␈α∀does␈α∪it␈α∀relate␈α∀to␈α∪the␈α∀language␈α∀the␈α∀system␈α∪is
␈↓ ↓H␈↓written in? (both written as BEINGs in INTERLISP.)

␈↓ ↓H␈↓Does␈α∩the␈α∩system␈α∪modify␈α∩as␈α∩well␈α∪as␈α∩write␈α∩code?␈α∩(yes,␈α∪but␈α∩not␈α∩as␈α∪its␈α∩major
␈↓ ↓H␈↓mechanism.)␈α⊃If␈α∩so,␈α⊃can␈α⊃it␈α∩modify␈α⊃anybody's,␈α⊃or␈α∩only␈α⊃those␈α⊃programs␈α∩it␈α⊃has
␈↓ ↓H␈↓written␈α↔itself?␈α↔ (only␈α⊗its␈α↔own,␈α↔and␈α⊗only␈α↔in␈α↔simple␈α⊗ways.)␈α↔What␈α↔is␈α⊗its


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 24␈↓ 	/REALITY:  RESULTS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓"style"␈α"of␈α"programming?␈α#(many␈α"supplementary␈α"comments,␈α#fairly␈α"clean
␈↓ ↓H␈↓structured␈α⊂programs␈α⊂only.)␈α⊂One␈α⊂also␈α⊂wishes␈α⊂to␈α⊂know␈α⊂the␈α⊂size␈α⊂of␈α⊂the␈α⊂tool␈α⊂as
␈↓ ↓H␈↓well␈α∪as␈α∀the␈α∪size␈α∀of␈α∪the␈α∀job:␈α∪How␈α∪does␈α∀the␈α∪system␈α∀size␈α∪compare␈α∀to␈α∪target
␈↓ ↓H␈↓program size? (one order of magnitude larger.)

␈↓ ↓H␈↓Efficiency␈α∩considerations␈α∩are␈α∩often␈α∩the␈α∩crucial␈α∩pragmatic␈α∩ones.␈α∩Economics
␈↓ ↓H␈↓and␈α⊃current␈α∩hardware␈α⊃restrict␈α∩the␈α⊃amount␈α∩of␈α⊃computation␈α∩which␈α⊃may␈α∩be␈α⊃done
␈↓ ↓H␈↓in␈α⊂toto;␈α⊂the␈α⊂expected␈α⊂lifetime␈α⊂of␈α⊂the␈α⊂universe␈α⊂restricts␈α⊂us␈α⊂from␈α⊂using␈α⊂the
␈↓ ↓H␈↓most␈α⊗"elegant"␈α⊗algorithms;␈α⊗and␈α⊗human␈α⊗patience␈α⊗restricts␈α⊗the␈α⊗interaction
␈↓ ↓H␈↓delay␈α↔time␈α_(to␈α↔a␈α↔minute␈α_or␈α↔two␈α_of␈α↔real␈α↔time).␈α_One␈α↔must␈α_therefore␈α↔ask
␈↓ ↓H␈↓things␈α⊂like␈α⊂how␈α⊂much␈α⊂time␈α⊂and␈α⊂space␈α⊂it␈α⊂requires,␈α⊂how␈α⊂long␈α⊂a␈α⊂delay␈α⊂there␈α⊂is
␈↓ ↓H␈↓between␈α⊃user␈α∩inputs,␈α⊃etc.␈α⊃(one␈α∩CPU␈α⊃hour,␈α⊃100K,␈α∩under␈α⊃a␈α⊃CPU␈α∩minute␈α⊃between
␈↓ ↓H␈↓responses.)

␈↓ ↓H␈↓The␈α↔second␈α↔class␈α_of␈α↔questions␈α↔concerns␈α↔the␈α_theoretical␈α↔side␈α↔of␈α_the␈α↔AP
␈↓ ↓H␈↓system.␈α_ What␈α_new␈α_ideas␈α_is␈α_it␈α_meant␈α_to␈α_experiment␈α_with?␈α_(this␈α_is␈α_the
␈↓ ↓H␈↓subject␈α⊂of␈α⊂most␈α⊂of␈α⊂the␈α⊂preceding␈α⊂text;␈α⊂see␈α⊂esp.␈α⊂section␈α⊂3.)␈α⊂How␈α⊂do␈α⊂each␈α⊂of
␈↓ ↓H␈↓these␈α↔ideas␈α↔fare?␈α⊗(many␈α↔surprises;␈α↔this␈α⊗is␈α↔the␈α↔subject␈α⊗of␈α↔most␈α↔of␈α⊗the
␈↓ ↓H␈↓remainder␈α∀of␈α∀this␈α∪paper;␈α∀see␈α∀esp.␈α∪section␈α∀8.)␈α∀Does␈α∪it␈α∀write␈α∀its␈α∀code␈α∪in
␈↓ ↓H␈↓the␈α↔right␈α_way?␈α↔ (it␈α↔asks␈α_the␈α↔right␈α_questions␈α↔of␈α↔the␈α_user␈α↔at␈α_just␈α↔the
␈↓ ↓H␈↓proper␈α⊂times␈α⊂with␈α⊂respect␈α⊂to␈α⊂the␈α⊂original␈α⊂protocol.)␈α⊂How␈α⊂extendable␈α⊂is␈α⊂it:
␈↓ ↓H␈↓how␈α⊂difficult␈α⊂is␈α⊂it␈α⊂to␈α⊂add␈α⊂new␈α⊂pieces␈α⊂of␈α⊂knowledge␈α⊂and␈α⊂to␈α⊂modify␈α⊂old␈α⊂ones?
␈↓ ↓H␈↓(theoretically␈α⊂easy,␈α⊂practically␈α⊂it␈α⊂requires␈α⊂familiarity␈α⊂with␈α⊂the␈α⊂system.)
␈↓ ↓H␈↓Could␈α∃it␈α∃write␈α∃programs␈α∃in␈α∀various␈α∃fields␈α∃(probably),␈α∃in␈α∃various␈α∀styles
␈↓ ↓H␈↓(possibly),␈α∪in␈α∪various␈α∪sizes?␈α∀ (the␈α∪three␈α∪target␈α∪programs␈α∪differ␈α∀by␈α∪less
␈↓ ↓H␈↓than one order of magnitude.)

␈↓ ↓H␈↓How␈α∩is␈α∩knowledge␈α∩represented␈α∩internally?␈α∩(BEINGs,␈α∩assertions,␈α∩demons.)␈α∩Is
␈↓ ↓H␈↓any␈α~of␈α~it␈α~duplicated?␈α~(not␈α≠much␈α~above␈α~the␈α~LISP␈α~language␈α≠level;␈α~some
␈↓ ↓H␈↓universal␈α⊗knowledge␈α⊗is␈α⊗factored␈α⊗out;␈α∃e.g.,␈α⊗how␈α⊗to␈α⊗CHOOSE-FROM␈α⊗a␈α⊗set␈α∃of
␈↓ ↓H␈↓BEINGs.)␈α→If␈α~so,␈α→what␈α→and␈α~why?␈α→(some,␈α→by␈α~laziness;␈α→e.g.,␈α→how␈α~to␈α→bind
␈↓ ↓H␈↓variables.)␈α≡Why␈α∨doesn't␈α≡this␈α∨system␈α≡solve␈α≡the␈α∨AP␈α≡problem?␈α∨(it␈α≡was
␈↓ ↓H␈↓mistakenly␈α⊃thought␈α∩that␈α⊃the␈α∩problems␈α⊃of␈α∩dialogue␈α⊃were␈α∩not␈α⊃central␈α∩to␈α⊃"the
␈↓ ↓H␈↓AP problem.")

␈↓ ↓H␈↓Detailed␈α∪answers␈α∪to␈α∪most␈α∀of␈α∪the␈α∪these␈α∪questions␈α∪are␈α∀scattered␈α∪throughout
␈↓ ↓H␈↓the␈α∀earlier␈α∀sections␈α∀of␈α∀this␈α∀paper.␈α∀ Below␈α∀are␈α∀its␈α∀answers␈α∀in␈α∀detail␈α∀to
␈↓ ↓H␈↓the remaining questions.

␈↓ ↓H␈↓Let␈α∃us␈α⊗briefly␈α∃describe␈α∃GI␈α⊗and␈α∃INF,␈α∃the␈α⊗second␈α∃and␈α∃third␈α⊗programs␈α∃PUP6
␈↓ ↓H␈↓synthesized.␈α⊂ GI␈α⊂is␈α⊂a␈α⊂simple␈α⊂grammatical␈α⊂inference␈α⊂program.␈α⊂It␈α⊂builds␈α⊂up␈α⊂a
␈↓ ↓H␈↓set␈α∪of␈α∪plausible␈α∪rules,␈α∪rather␈α∪than␈α∪enumerating␈α∪through␈α∪the␈α∪space␈α∪of␈α∩all
␈↓ ↓H␈↓grammars.␈α∀Yet␈α∀it␈α∀lacks␈α∀most␈α∀of␈α∀the␈α∀"tricks"␈α∀of␈α∀the␈α∀best␈α∀g.i.␈α∀ programs.
␈↓ ↓H␈↓The␈α⊂user␈α⊂repeatedly␈α⊂specifies␈α⊂a␈α⊂string,␈α⊂labelled␈α⊂LEGAL,␈α⊂ILLEGAL,␈α⊂or␈α⊂??.␈α⊂In
␈↓ ↓H␈↓the␈α⊃latter␈α⊃case,␈α⊃GI␈α∩must␈α⊃print␈α⊃out␈α⊃its␈α∩guess␈α⊃and␈α⊃accept␈α⊃the␈α∩correct␈α⊃label
␈↓ ↓H␈↓from␈α∀the␈α∀user.␈α∪ In␈α∀all␈α∀three␈α∪cases,␈α∀it␈α∀must␈α∪update␈α∀its␈α∀set␈α∀of␈α∪plausible
␈↓ ↓H␈↓rules␈α∪to␈α∪be␈α∪at␈α∪least␈α∪consistent␈α∪with␈α∪all␈α∪positive␈α∪and␈α∪negative␈α∩instances


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 25␈↓ 	/REALITY:  RESULTS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓observed.␈α⊂In␈α⊂some␈α⊂versions␈α⊂of␈α⊂GI␈α⊂the␈α⊂user␈α⊂coaxes␈α⊂PUP6␈α⊂to␈α⊂generate,␈α⊂a␈α⊂parse
␈↓ ↓H␈↓tree␈α∀may␈α∀be␈α∀maintained␈α∀and␈α∀inspected;␈α∀in␈α∀other␈α∀versions,␈α∀just␈α∀a␈α∀list␈α∀of
␈↓ ↓H␈↓the rules used during a parse is kept.

␈↓ ↓H␈↓INF␈α∃is␈α∃a␈α∃data-retrieval-on-keys␈α∃system.␈α∀ The␈α∃user␈α∃repeatedly␈α∃types␈α∃in␈α∀a
␈↓ ↓H␈↓request␈α∃to␈α∃insert,␈α∃delete,␈α∃or␈α∀inspect␈α∃a␈α∃record␈α∃(e.g.,␈α∃INSERT:␈α∀PASSENGER
␈↓ ↓H␈↓Jones␈α⊂FLIGHT␈α⊂741␈α⊂FROM␈α⊂SFO␈α⊂TO␈α⊂LAX␈α⊂CARRIER␈α⊂TWA␈α⊂LEAVE␈α⊂7:15␈α⊂ARRIVE␈α⊂8:00).␈α⊂ Any
␈↓ ↓H␈↓unspecified␈α≠fields␈α≠are␈α≠treated␈α≤as␈α≠dont't␈α≠cares;␈α≠thus␈α≠the␈α≤request␈α≠is
␈↓ ↓H␈↓matched against entries in the data base.

␈↓ ↓H␈↓The␈α∩table␈α∪below␈α∩shows␈α∪how␈α∩each␈α∪type␈α∩of␈α∪knowledge␈α∩was␈α∪used␈α∩in␈α∪writing␈α∩the
␈↓ ↓H␈↓three target programs.  All numbers refer to BEINGs.

␈↓ ↓H␈↓ε␈α?␈α?␈α∂        ␈↓πU  S  E  D     I  N     S  Y  N  T  H  E  S  I  Z  I  N  G␈↓ε

␈↓ ↓H␈↓εTYPE OF          CF    CF    CF    CF     GI    INF     not     Crea    Crea    Crea    Total
␈↓ ↓H␈↓εKNOWLEDGE        GI    GI   INF   only   only   only    used    -ted    -ted    -ted    BEINGs
␈↓ ↓H␈↓ε                INF   only   only                       ever    in CF   in GI   in INF

␈↓ ↓H␈↓εProgramming      39     7     5     5     3      1       14       52      27      21      174
␈↓ ↓H␈↓εDomain-Specific   0     3     0     9     8      1        5        4      10       3       43
␈↓ ↓H␈↓εTotal BEINGs     39    10     5    14    11      2       19       56      37      24      217

␈↓ ↓H␈↓The␈α⊗high␈α⊗percentage␈α⊗of␈α⊗programming␈α∃BEINGs␈α⊗which␈α⊗were␈α⊗used␈α⊗in␈α⊗all␈α∃three
␈↓ ↓H␈↓dialogues␈α∪is␈α∪exciting.␈α∪ The␈α∀three␈α∪domain-specific␈α∪BEINGs␈α∪used␈α∪in␈α∀both␈α∪CF
␈↓ ↓H␈↓and␈α~GI␈α→sessions␈α~indicate␈α~that␈α→they␈α~may␈α→be␈α~Inductive␈α~Inference␈α→domain
␈↓ ↓H␈↓specific.␈α∀ They␈α∃aren't␈α∀used␈α∀in␈α∃INF,␈α∀which␈α∀is␈α∃not␈α∀an␈α∃inductive␈α∀inference
␈↓ ↓H␈↓task. All three deal with partitioning a domain.

␈↓ ↓H␈↓A␈α⊂specialization␈α⊂of␈α⊂a␈α⊂general␈α⊂programming␈α⊂BEING␈α⊂is␈α⊂listed␈α⊂as␈α⊂a␈α⊂programming
␈↓ ↓H␈↓BEING␈α∪still␈α∪(in␈α∩the␈α∪CREATED␈α∪columns␈α∩of␈α∪the␈α∪above␈α∩table.)␈α∪This␈α∪is␈α∩because
␈↓ ↓H␈↓it␈α∪remains␈α∪sufficiently␈α∪independent␈α∀to␈α∪be␈α∪used␈α∪in␈α∪many␈α∀ways,␈α∪conceivably
␈↓ ↓H␈↓in many different programs.

␈↓ ↓H␈↓The␈α∪style␈α∪of␈α∪the␈α∪synthesized␈α∪programs␈α∪is␈α∪constrained␈α∪since␈α∪all␈α∪code␈α∩must
␈↓ ↓H␈↓be␈α∪BEINGs.␈α∪At␈α∪a␈α∪lower␈α∪level,␈α∪there␈α∪are␈α∪many␈α∪trivial␈α∪inefficiencies␈α∩which
␈↓ ↓H␈↓are␈α_passed␈α_through␈α_a␈α_BEING␈α_which␈α_is␈α_to␈α_optimize␈α_LISP␈α_programs␈α_out␈α_of
␈↓ ↓H␈↓context,␈α⊃at␈α⊃a␈α⊃low␈α∩level.␈α⊃ This␈α⊃BEING␈α⊃is␈α∩vacuous␈α⊃now,␈α⊃but␈α⊃may␈α∩soon␈α⊃contain
␈↓ ↓H␈↓a␈α⊂LISP␈α⊂optimizer␈α⊂being␈α⊂written␈α⊂by␈α⊂A.␈α⊂ Cohn␈α⊂of␈α⊂the␈α⊂SAIL␈α⊂AP␈α⊂group.␈α⊂Low␈α⊂level
␈↓ ↓H␈↓efficiency␈α(was␈α(intentionally␈α(ignored␈α(to␈α(expedite␈α(work␈α(on␈α(PUP6.
␈↓ ↓H␈↓Nevertheless,␈α∪the␈α∪final␈α∩code␈α∪produced␈α∪runs␈α∩in␈α∪about␈α∪the␈α∩same␈α∪time␈α∪as␈α∩the
␈↓ ↓H␈↓hand-coded␈α⊂versions␈α⊂(e.g.,␈α⊂a␈α⊂few␈α⊂seconds␈α⊂per␈α⊂scene␈α⊂for␈α⊂CF).␈α⊂ It␈α⊂is␈α⊂several
␈↓ ↓H␈↓times␈α∃as␈α⊗long,␈α∃though,␈α∃since␈α⊗it␈α∃must␈α∃be␈α⊗able␈α∃to␈α∃answer␈α⊗questions␈α∃about
␈↓ ↓H␈↓what␈α↔it's␈α↔doing␈α_as␈α↔it␈α↔runs.␈α↔The␈α_program␈α↔produced␈α↔by␈α_the␈α↔system-player
␈↓ ↓H␈↓during the original protocol lacked this ability, of course.

␈↓ ↓H␈↓Although␈α_BEINGs␈α_can␈α_theoretically␈α_handle␈α_user␈α_errors,␈α_PUP6␈α_was␈α_set␈α_up
␈↓ ↓H␈↓expecting␈α∀that␈α∀the␈α∀user␈α∀would␈α∀never␈α∀err␈α∀or␈α∀forget.␈α∀ He␈α∀could,␈α∀after␈α∀the


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 26␈↓ 	/REALITY:  RESULTS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓program␈α∀was␈α∀finished,␈α∀try␈α∀it␈α∀out␈α∀and␈α∀describe␈α∀how␈α∀he␈α∀wished␈α∀it␈α∀changed.
␈↓ ↓H␈↓Occasionally,␈α_PUP6␈α_actually␈α_make␈α_the␈α_right␈α_modifications.␈α_For␈α_example,
␈↓ ↓H␈↓INF,␈α~the␈α~simple␈α~data␈α~storage␈α≠and␈α~retrieval␈α~on␈α~keys␈α~system␈α≠which␈α~was
␈↓ ↓H␈↓written,␈α≤was␈α≤supposed␈α≤to␈α≤accept,␈α≤access,␈α≤and␈α≤eliminate␈α≤reservations.
␈↓ ↓H␈↓After␈α⊃the␈α∩synthesis␈α⊃is␈α⊃finished,␈α∩the␈α⊃user␈α⊃tries␈α∩out␈α⊃the␈α⊃program␈α∩and␈α⊃finds
␈↓ ↓H␈↓that␈α↔he␈α↔is␈α⊗unable␈α↔to␈α↔delete␈α⊗more␈α↔than␈α↔one␈α⊗reservation␈α↔with␈α↔any␈α⊗single
␈↓ ↓H␈↓command.␈α⊂He␈α⊂complains␈α⊂about␈α⊂this,␈α⊂and␈α⊂PUP6␈α⊂modifies␈α⊂the␈α⊂program␈α⊂so␈α⊂that␈α⊂he
␈↓ ↓H␈↓may␈α⊃specify␈α∩a␈α⊃pattern,␈α∩and␈α⊃all␈α∩reservations␈α⊃matching␈α∩that␈α⊃pattern␈α∩will␈α⊃be
␈↓ ↓H␈↓purged.␈α⊂ While␈α⊂assumptions␈α⊂of␈α⊂absolute␈α⊂user␈α⊂reliability␈α⊂are␈α⊂reasonable␈α⊂for
␈↓ ↓H␈↓little␈α⊃programs,␈α⊃they␈α⊃break␈α∩down␈α⊃when␈α⊃the␈α⊃tasks␈α∩reach␈α⊃the␈α⊃size␈α⊃of␈α∩tens␈α⊃of
␈↓ ↓H␈↓pages and hours.

␈↓ ↓H␈↓Good␈α⊂measures␈α⊂of␈α⊂concentration␈α⊂of␈α⊂intelligence␈α⊂are␈α⊂not␈α⊂yet␈α⊂available.␈α⊂ The
␈↓ ↓H␈↓only␈α∩alternative␈α∩is␈α∩to␈α⊃present␈α∩ephemeral␈α∩numerical␈α∩efficiency␈α∩data,␈α⊃which
␈↓ ↓H␈↓now␈α follows.␈α PUP6␈α is␈α 200␈α pages␈α long␈α when␈α PRETTY-PRINTED,␈α and␈α has
␈↓ ↓H␈↓synthesized␈α∩three␈α∪programs,␈α∩7,␈α∪20,␈α∩and␈α∪30␈α∩pages␈α∪long␈α∩(1,␈α∪4,␈α∩and␈α∪6␈α∩pages,
␈↓ ↓H␈↓when coded by hand.)

␈↓ ↓H␈↓Two␈α∩important␈α⊃factors␈α∩are␈α∩omitted␈α⊃when␈α∩simply␈α⊃comparing␈α∩system␈α∩and␈α⊃target
␈↓ ↓H␈↓lengths.␈α∃First,␈α∃one␈α∃might␈α∃improve␈α∀any␈α∃such␈α∃measure␈α∃by␈α∃simply␈α∀decreasing
␈↓ ↓H␈↓the␈α∩size␈α∪of␈α∩a␈α∪given␈α∩system.␈α∪This␈α∩is␈α∪wrong,␈α∩since,␈α∪e.g.,␈α∩removing␈α∪all␈α∩the
␈↓ ↓H␈↓comments␈α⊗from␈α⊗a␈α⊗program␈α⊗shouldn't␈α⊗increase␈α⊗its␈α⊗intelligence!␈α⊗ Secondly,
␈↓ ↓H␈↓the␈α≡total␈α≡amount␈α≡of␈α∨distinct␈α≡target␈α≡programs␈α≡should␈α∨be␈α≡considered.
␈↓ ↓H␈↓Compilers␈α⊂turn␈α⊂out␈α⊂programs␈α⊂small␈α⊂compared␈α⊂to␈α⊂themselves,␈α⊂but␈α⊂are␈α⊂valuable
␈↓ ↓H␈↓because␈α⊃of␈α∩the␈α⊃vast␈α⊃variety␈α∩of␈α⊃such␈α⊃programs␈α∩they␈α⊃can␈α⊃put␈α∩together.␈α⊃ This
␈↓ ↓H␈↓factor␈α→reflects␈α_how␈α→much␈α→of␈α_the␈α→"guts"␈α_of␈α→the␈α→system␈α_can␈α→be␈α→used␈α_in
␈↓ ↓H␈↓writing many programs.

␈↓ ↓H␈↓PUP6␈α⊂takes␈α⊂60␈α⊂cpu␈α⊂minutes␈α⊂to␈α⊂produce␈α⊂CF␈α⊂(compiled␈α⊂INTERLISP␈α⊂code,␈α⊂run␈α⊂on␈α⊂a
␈↓ ↓H␈↓PDP-10␈α∪TENEX␈α∪system).␈α∪During␈α∪this␈α∪time,␈α∪300K␈α∪characters␈α∪get␈α∪typed␈α∪out␈α∩to
␈↓ ↓H␈↓the␈α⊂user,␈α⊂who␈α⊂reponds␈α⊂with␈α⊂about␈α⊂4K␈α⊂himself.␈α⊂The␈α⊂dialogue␈α⊂lengths␈α⊂are␈α⊂best
␈↓ ↓H␈↓specified␈α⊃in␈α∩characters,␈α⊃since␈α∩often␈α⊃the␈α∩user␈α⊃will␈α∩supply␈α⊃simply␈α∩a␈α⊃number
␈↓ ↓H␈↓or␈α↔a␈α_letter␈α↔or␈α↔a␈α_YES/NO␈α↔reply.␈α_ Dividing␈α↔these␈α↔by␈α_a␈α↔hundred,␈α_one␈α↔can
␈↓ ↓H␈↓relate␈α↔them␈α↔to␈α_target␈α↔and␈α↔system␈α↔lengths␈α_in␈α↔lines.␈α↔Even␈α_the␈α↔character
␈↓ ↓H␈↓counts␈α⊂are␈α⊂very␈α⊂rough,␈α⊂because␈α⊂the␈α⊂format␈α⊂of␈α⊂the␈α⊂AP␈α⊂dialogue␈α⊂can␈α⊂easily␈α⊂be
␈↓ ↓H␈↓varied␈α∪by␈α∪a␈α∩couple␈α∪orders␈α∪of␈α∩magnitude.␈α∪ The␈α∪mean␈α∩wait␈α∪time␈α∪(between␈α∩the
␈↓ ↓H␈↓user's␈α⊃input␈α∩and␈α⊃the␈α∩next␈α⊃machine␈α∩output)␈α⊃is␈α∩several␈α⊃seconds.␈α∩The␈α⊃longest
␈↓ ↓H␈↓delay␈α⊂between␈α⊂successive␈α⊂user␈α⊂inputs␈α⊂is␈α⊂1␈α⊂CPU␈α⊂minute.␈α⊂ Unfortunately,␈α⊂PUP6
␈↓ ↓H␈↓requires␈α~100K␈α→to␈α~run␈α~in,␈α→which␈α~(with␈α→INTERLISP)␈α~exhausts␈α~the␈α→virtual
␈↓ ↓H␈↓memory␈α⊂of␈α⊂the␈α⊂current␈α⊂hardware␈α⊂being␈α⊂used.␈α⊂ One␈α⊂would␈α⊂lose␈α⊂vast␈α⊂amounts␈α⊂of
␈↓ ↓H␈↓time␈α≠by␈α≠using␈α~intermediate␈α≠storage␈α≠devices␈α~or␈α≠by␈α≠running␈α~consecutive
␈↓ ↓H␈↓communicating␈α∀jobs.␈α∪Efficient␈α∀use␈α∪of␈α∀multiple␈α∪processors␈α∀and␈α∀of␈α∪extended
␈↓ ↓H␈↓core storage might be made.

␈↓ ↓H␈↓INF␈α∃was␈α⊗one␈α∃fifth␈α∃the␈α⊗size␈α∃of␈α∃CF,␈α⊗and␈α∃took␈α∃about␈α⊗a␈α∃seventh␈α∃as␈α⊗long␈α∃to
␈↓ ↓H␈↓generate.␈α⊃The␈α∩dialogue␈α⊃was␈α⊃shorter␈α∩by␈α⊃a␈α⊃factor␈α∩of␈α⊃three.␈α⊃The␈α∩dialogue␈α⊃for
␈↓ ↓H␈↓the␈α⊂CF␈α⊂target␈α⊂program␈α⊂was␈α⊂too␈α⊂long␈α⊂and␈α⊂tiresome;␈α⊂the␈α⊂problem␈α⊂was␈α⊂even␈α⊂more
␈↓ ↓H␈↓acute for the INF program.

␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 27␈↓ 	/REALITY:  RESULTS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓Most␈α∪of␈α∪the␈α∩theoretical␈α∪questions␈α∪are␈α∩answered␈α∪by␈α∪the␈α∩very␈α∪design␈α∪of␈α∩the
␈↓ ↓H␈↓system.␈α≠Its␈α≠ideational␈α~foundation␈α≠has␈α≠been␈α~discussed.␈α≠ When␈α≠the␈α~user
␈↓ ↓H␈↓sticks␈α∀close␈α∃to␈α∀the␈α∀original␈α∃protocol,␈α∀PUP6␈α∀asks␈α∃the␈α∀right␈α∃questions␈α∀at
␈↓ ↓H␈↓the␈α⊃right␈α∩times␈α⊃because␈α∩of␈α⊃its␈α∩genesis␈α⊃from␈α∩that␈α⊃annotated␈α∩protocol.␈α⊃ The
␈↓ ↓H␈↓second␈α⊂and␈α⊂third␈α⊂programs␈α⊂were␈α⊂attempted␈α⊂only␈α⊂to␈α⊂test␈α⊂its␈α⊂flexibility,␈α⊂and
␈↓ ↓H␈↓the results were mixed.

␈↓ ↓H␈↓First␈α⊃the␈α⊃bright␈α⊃side.␈α⊃The␈α⊃increment␈α∩to␈α⊃PUP6␈α⊃to␈α⊃enable␈α⊃it␈α⊃to␈α⊃write␈α∩the␈α⊃GI
␈↓ ↓H␈↓and␈α∪the␈α∪INF␈α∪programs␈α∀is␈α∪encouragingly␈α∪small.␈α∪Almost␈α∪all␈α∀the␈α∪programming-
␈↓ ↓H␈↓knowledge␈α∪BEINGs␈α∪are␈α∩called␈α∪in␈α∪writing␈α∩more␈α∪than␈α∪one␈α∩of␈α∪the␈α∪programs.␈α∩It
␈↓ ↓H␈↓is␈α→now␈α→clear␈α_that␈α→very␈α→domain-specific␈α→BEINGs␈α_were␈α→in␈α→control␈α→at␈α_the
␈↓ ↓H␈↓early,␈α⊂high␈α⊂levels.␈α⊂Later,␈α⊂more␈α⊂general␈α⊂BEINGs␈α⊂took␈α⊂over,␈α⊂followed␈α⊂by␈α⊂pure
␈↓ ↓H␈↓programming␈α%BEINGs.␈α$ The␈α%middle␈α$category␈α%would␈α%include␈α$inductive-
␈↓ ↓H␈↓inference-specific BEINGs like PARTITION_A_DOMAIN.

␈↓ ↓H␈↓Regrettably,␈α⊗incrementing␈α⊗the␈α⊗system␈α⊗with␈α⊗new␈α⊗domain-specific␈α⊗BEINGs␈α⊗is
␈↓ ↓H␈↓not␈α⊂feasable␈α⊂for␈α⊂the␈α⊂average␈α⊂user.␈α⊂ To␈α⊂add␈α⊂a␈α⊂BEING,␈α⊂he␈α⊂must␈α⊂specify␈α⊂all␈α⊂of
␈↓ ↓H␈↓its␈α∀relevant␈α∀parts.␈α∀Each␈α∀is␈α∀inputted␈α∀either␈α∀as␈α∀LISP␈α∀code,␈α∀as␈α∀an␈α∀English
␈↓ ↓H␈↓sentence␈α⊂PUP6␈α⊂is␈α⊂capable␈α⊂of␈α⊂interpreting,␈α⊂an␈α⊂English␈α⊂sentence␈α⊂PUP6␈α⊂is␈α⊂just
␈↓ ↓H␈↓supposed␈α⊃to␈α⊃remember␈α⊃as␈α⊃a␈α⊃canned␈α∩response,␈α⊃or␈α⊃by␈α⊃pointing␈α⊃to␈α⊃a␈α⊃part␈α∩of␈α⊃an
␈↓ ↓H␈↓existing␈α⊃BEING␈α∩and␈α⊃saying␈α∩"like␈α⊃that␈α∩one,␈α⊃except␈α∩...",␈α⊃where␈α∩the␈α⊃ellipsis
␈↓ ↓H␈↓must␈α≥be␈α≥very␈α≥simple.␈α≥ The␈α≤interactions␈α≥between␈α≥the␈α≥BEINGs,␈α≥and␈α≤the
␈↓ ↓H␈↓existing␈α_set␈α_of␈α_BEINGs,␈α_need␈α_not␈α_be␈α_fully␈α_understood;␈α_but␈α_the␈α_set␈α_of
␈↓ ↓H␈↓allowable␈α∩assertion␈α⊃templates,␈α∩the␈α∩mechanisms␈α⊃by␈α∩which␈α⊃each␈α∩part␈α∩is␈α⊃used,
␈↓ ↓H␈↓the␈α∪special␈α∪data␈α∪types␈α∀involved␈α∪(VECTOR,␈α∪TUPLE),␈α∪and␈α∪the␈α∀precise␈α∪actions
␈↓ ↓H␈↓of␈α⊗each␈α⊗new␈α⊗part␈α⊗␈↓βmust␈↓␈α⊗be␈α⊗known␈α⊗in␈α⊗order␈α⊗to␈α⊗safely␈α⊗inject␈α⊗a␈α⊗new␈α∃BEING.
␈↓ ↓H␈↓This␈α∩may␈α∩be␈α∪a␈α∩result␈α∩of␈α∪the␈α∩small␈α∩amount␈α∩of␈α∪knowledge␈α∩in␈α∩PUP6.␈α∪One␈α∩would
␈↓ ↓H␈↓hope␈α∀that␈α∀a␈α∪BEINGs␈α∀system␈α∀which␈α∪was␈α∀expert␈α∀in␈α∪a␈α∀domain␈α∀could␈α∀assist␈α∪the
␈↓ ↓H␈↓user␈α⊂in␈α⊂adding␈α⊂new␈α⊂domain-specific␈α⊂BEINGs,␈α⊂in␈α⊂the␈α⊂same␈α⊂way␈α⊂that␈α⊂the␈α⊂BEINGs
␈↓ ↓H␈↓which make up the target code are synthesized, through dialogue.



















␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 28␈↓ 	/REALITY:  RESULTS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓␈↓↓8. THEORY: CONCLUSIONS␈↓

␈↓ ↓H␈↓The␈α∪strengths␈α∪and␈α∪weaknesses␈α∪of␈α∪both␈α∪BEINGs␈α∪and␈α∪PUP6␈α∪are␈α∪reviewed.␈α∩ This
␈↓ ↓H␈↓experiment␈α⊂has␈α⊂helped␈α⊂clarify␈α⊂some␈α⊂of␈α⊂the␈α⊂potential␈α⊂problems␈α⊂facing␈α⊂future
␈↓ ↓H␈↓AP work.

␈↓ ↓H␈↓While␈α⊂the␈α⊂number␈α⊂of␈α⊂BEING-parts␈α⊂is␈α⊂unimportant,␈α⊂its␈α⊂magnitude␈α⊂(a␈α⊂few␈α⊂tens)
␈↓ ↓H␈↓may␈α∩have␈α∪significance␈α∩to␈α∪AP.␈α∩ The␈α∪fact␈α∩that␈α∪is␈α∩isn't␈α∪~1␈α∩may␈α∪help␈α∩explain
␈↓ ↓H␈↓the␈α∀difficulty␈α∪with␈α∀predicate␈α∪calculus␈α∀representations;␈α∪the␈α∀fact␈α∀that␈α∪it
␈↓ ↓H␈↓isn't ~1000 may mean that the AP problem is tractible.

␈↓ ↓H␈↓Some␈α↔of␈α↔the␈α⊗ideas␈α↔discussed␈α↔at␈α⊗the␈α↔beginning␈α↔of␈α⊗the␈α↔paper␈α↔have␈α⊗proven
␈↓ ↓H␈↓themselves␈α→to␈α→be␈α_useful␈α→in␈α→getting␈α→PUP6␈α_to␈α→work.␈α→Little␈α→programs␈α_can
␈↓ ↓H␈↓indeed␈α⊂be␈α⊂treated␈α⊂as␈α⊂if␈α⊂their␈α⊂essence␈α⊂is␈α⊂nothing␈α⊂more␈α⊂than␈α⊂a␈α⊂collection␈α⊂of
␈↓ ↓H␈↓answers.␈α∀ The␈α∪gain␈α∀from␈α∪standardization␈α∀is␈α∪conceptually␈α∀easy␈α∀addition␈α∪of
␈↓ ↓H␈↓pieces␈α⊂to␈α⊂the␈α⊂system;␈α⊂one␈α⊂"merely"␈α⊂adds␈α⊂new␈α⊂BEINGs␈α⊂to␈α⊂the␈α⊂community.␈α⊂Their
␈↓ ↓H␈↓interactions␈α⊃with␈α∩all␈α⊃the␈α∩existing␈α⊃BEINGs␈α∩needn't␈α⊃be␈α∩known␈α⊃in␈α∩advance.␈α⊃As
␈↓ ↓H␈↓was␈α∪discussed␈α∪in␈α∪the␈α∪previous␈α∪section,␈α∪the␈α∪actual␈α∪addition␈α∪is␈α∪beyond␈α∩the
␈↓ ↓H␈↓power of the untrained user.

␈↓ ↓H␈↓Indications␈α⊃are␈α⊂that␈α⊃one␈α⊂␈↓βcan␈↓␈α⊃locate␈α⊂relevant␈α⊃information␈α⊂by␈α⊃organizing␈α⊂the
␈↓ ↓H␈↓knowledge␈α⊃in␈α∩a␈α⊃pool,␈α∩with␈α⊃each␈α∩piece␈α⊃(i)␈α∩responsible␈α⊃for␈α∩recognizing␈α⊃when
␈↓ ↓H␈↓it␈α⊂is␈α⊂relevant␈α⊂and␈α⊂(ii)␈α⊂indicating␈α⊂new␈α⊂relevant␈α⊂information␈α⊂indirectly␈α⊂via
␈↓ ↓H␈↓nondeterministic␈α∪pattern-directed␈α∪retrievals␈α∩and␈α∪assertions.␈α∪ Notice␈α∩that
␈↓ ↓H␈↓this␈α⊃puts␈α⊃all␈α⊃control␈α∩structure␈α⊃into␈α⊃the␈α⊃hands␈α∩of␈α⊃the␈α⊃BEINGs;␈α⊃there␈α∩is␈α⊃no
␈↓ ↓H␈↓central␈α⊃monitor␈α∩in␈α⊃PUP6.␈α∩ A␈α⊃BEING's␈α∩answers␈α⊃may␈α∩at␈α⊃various␈α∩times␈α⊃indicate
␈↓ ↓H␈↓that␈α∃it␈α∀should␈α∃be␈α∀chosen␈α∃to␈α∃be␈α∀in␈α∃control,␈α∀and␈α∃it␈α∀will␈α∃then␈α∃take␈α∀over.
␈↓ ↓H␈↓Notice␈α∩also␈α⊃that␈α∩this␈α∩relevancy␈α⊃problem␈α∩is␈α⊃central␈α∩to␈α∩program␈α⊃maintenance
␈↓ ↓H␈↓as␈α⊂well␈α⊂as␈α⊂synthesis.␈α⊂It␈α⊂is␈α⊂not␈α⊂clear␈α⊂whether␈α⊂or␈α⊂not␈α⊂this␈α⊂really␈α⊂beats␈α⊂the
␈↓ ↓H␈↓exponential growth of this problem.

␈↓ ↓H␈↓The␈α∪fact␈α∀that␈α∪target␈α∀code␈α∪is␈α∀in␈α∪the␈α∪format␈α∀of␈α∪BEINGs␈α∀limits␈α∪the␈α∀size␈α∪of
␈↓ ↓H␈↓the␈α∪target␈α∪programs␈α∩(≥␈α∪one␈α∪page)␈α∩and␈α∪their␈α∪efficiency␈α∩(a␈α∪BEING-call␈α∪is␈α∩a
␈↓ ↓H␈↓very␈α→slow␈α→and␈α_intricate␈α→process)␈α→and␈α→of␈α_course␈α→their␈α→style.␈α→The␈α_most
␈↓ ↓H␈↓startling␈α#result␈α#--␈α#which␈α$should␈α#have␈α#been␈α#forseen␈α#--␈α$was␈α#that
␈↓ ↓H␈↓"intelligent"␈α∀target␈α∪code␈α∀is␈α∪synthesized.␈α∀This␈α∪was␈α∀mentioned␈α∀casually␈α∪in
␈↓ ↓H␈↓the␈α∪IDEAS␈α∪section,␈α∩but␈α∪its␈α∪importance␈α∩is␈α∪clear:␈α∪the␈α∩target␈α∪code␈α∪is␈α∩self-
␈↓ ↓H␈↓commenting␈α⊃in␈α∩the␈α⊃strong␈α⊃sense␈α∩that␈α⊃the␈α⊃generated␈α∩code␈α⊃can␈α⊃answer␈α∩any␈α⊃(of
␈↓ ↓H␈↓our␈α⊂set␈α⊂of␈α⊂29)␈α⊂questions␈α⊂about␈α⊂itself.␈α⊂ Those␈α⊂which␈α⊂make␈α⊂sense␈α⊂at␈α⊂compile-
␈↓ ↓H␈↓time␈α∃can␈α⊗be␈α∃asked␈α∃then;␈α⊗those␈α∃which␈α∃make␈α⊗sense␈α∃during␈α∃execution␈α⊗may␈α∃be
␈↓ ↓H␈↓asked␈α∃then.␈α∃ For␈α∃example,␈α∃CF␈α∀begins␈α∃running.␈α∃ After␈α∃several␈α∃scenes␈α∀have
␈↓ ↓H␈↓been␈α∩processed,␈α∪CF␈α∩is␈α∪waiting␈α∩for␈α∪a␈α∩new␈α∪one.␈α∩ If␈α∪the␈α∩user␈α∪interrupts␈α∩and
␈↓ ↓H␈↓asks␈α∩what␈α∩it␈α∪is␈α∩doing,␈α∩CF␈α∪will␈α∩reply␈α∩"awaiting␈α∩user␈α∪input␈α∩of␈α∩a␈α∪brand␈α∩new
␈↓ ↓H␈↓scene."␈α∩One␈α∪can␈α∩ask␈α∪why,␈α∩how,␈α∪who␈α∩will␈α∪be␈α∩affected,␈α∪and␈α∩so␈α∪on,␈α∩interrupt
␈↓ ↓H␈↓as␈α∪frequently␈α∪as␈α∩desired␈α∪--␈α∪even␈α∩after␈α∪each␈α∪transfer␈α∩of␈α∪control␈α∪from␈α∩one
␈↓ ↓H␈↓BEING␈α≡to␈α∨another.␈α≡The␈α∨actual␈α≡questions␈α≡and␈α∨responses␈α≡are␈α∨not␈α≡very
␈↓ ↓H␈↓impressive,␈α⊃but␈α⊃they␈α⊃are␈α⊃at␈α⊃least␈α∩at␈α⊃the␈α⊃same␈α⊃level␈α⊃as␈α⊃those␈α⊃which␈α∩can␈α⊃be
␈↓ ↓H␈↓gotten from PUP6 itself as it runs.

␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 29␈↓ λ⎇THEORY:  CONCLUSIONS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓The␈α∪set␈α∀of␈α∪questions␈α∀the␈α∪user␈α∀was␈α∪expected␈α∪to␈α∀want␈α∪to␈α∀ask␈α∪the␈α∀system␈α∪is
␈↓ ↓H␈↓similar␈α↔to␈α↔the␈α⊗questions␈α↔one␈α↔BEING␈α⊗wants␈α↔to␈α↔ask␈α⊗another.␈α↔ So␈α↔when␈α⊗the
␈↓ ↓H␈↓"nice"␈α⊂user␈α⊂interrupts,␈α⊂his␈α⊂questions␈α⊂are␈α⊂almost␈α⊂always␈α⊂a␈α⊂simple␈α⊂retrieval
␈↓ ↓H␈↓from␈α∀a␈α∀property␈α∀list␈α∀(a␈α∀GETP␈α∀or␈α∀a␈α∀composition␈α∀like␈α∀EVAL␈GETP).␈α∀When␈α∀the
␈↓ ↓H␈↓average user interrupts, his questions are often unintelligible to PUP6.

␈↓ ↓H␈↓Meaningful␈α∪use␈α∪of␈α∪comments␈α∪proved␈α∪helpful.␈α∪As␈α∪an␈α∪example,␈α∪the␈α∪comment␈α∩at
␈↓ ↓H␈↓the␈α∩end␈α∪of␈α∩the␈α∪main␈α∩outer␈α∪loop␈α∩was␈α∪"COMMENT,␈α∩INFINITE␈α∪LOOP␈α∩IN␈α∪THIS␈α∩PROG"
␈↓ ↓H␈↓(see␈α⊂page␈α⊂A5.10)␈α⊂for␈α⊂most␈α⊂of␈α⊂the␈α⊂session.␈α⊂Near␈α⊂the␈α⊂end␈α⊂of␈α⊂the␈α⊂session,␈α⊂the
␈↓ ↓H␈↓CLARIFY_IMPROBABLE_SITUATION␈α∩BEING␈α∩recognizes␈α∩this␈α∩as␈α∩a␈α∩warning,␈α∩works␈α∩on
␈↓ ↓H␈↓introducing␈α≥a␈α≥breakaway␈α≥test,␈α≥and␈α≤then␈α≥replaces␈α≥the␈α≥comment␈α≥by␈α≤one
␈↓ ↓H␈↓indicating␈α⊗that␈α↔no␈α⊗infinite␈α↔loop␈α⊗exists␈α⊗there␈α↔anymore␈α⊗(see␈α↔page␈α⊗A4.4).
␈↓ ↓H␈↓The␈α⊂advantage␈α⊂to␈α⊂embedding␈α⊂our␈α⊂insertions␈α⊂in␈α⊂the␈α⊂code␈α⊂this␈α⊂way␈α⊂is␈α⊂that,␈α⊂at
␈↓ ↓H␈↓any␈α⊃stage,␈α∩the␈α⊃user␈α⊃can␈α∩inspect␈α⊃the␈α⊃code␈α∩and␈α⊃get␈α⊃something␈α∩meaningful␈α⊃out
␈↓ ↓H␈↓of the comments which are present.

␈↓ ↓H␈↓The␈α∀careful␈α∀bookkeeping␈α∀actually␈α∀did␈α∀eliminate␈α∀some␈α∀carelessness␈α∀errors,
␈↓ ↓H␈↓though␈α~it␈α~had␈α~no␈α~effect␈α≠on␈α~user␈α~errors␈α~or␈α~later␈α≠program␈α~maintenance
␈↓ ↓H␈↓directives.␈α≡ These␈α≡latter␈α≡processes␈α≡are␈α≡less␈α≡ill-defined␈α≡than␈α≡blind
␈↓ ↓H␈↓debugging,␈α"and␈α!in␈α"fact␈α"are␈α!about␈α"the␈α!same␈α"as␈α"programming␈α!itself
␈↓ ↓H␈↓[Dijkstra].␈α∩ The␈α⊃deferral␈α∩of␈α∩decisions␈α⊃has␈α∩the␈α⊃nice␈α∩corollary␈α∩of␈α⊃reducing
␈↓ ↓H␈↓(though not minimizing) communication with the slow user channel.

␈↓ ↓H␈↓Synthesizing␈α∪a␈α∪new,␈α∪clean␈α∀target␈α∪program␈α∪probably␈α∪would␈α∪require␈α∀adding␈α∪a
␈↓ ↓H␈↓few␈α≠domain-independent␈α≤BEINGs␈α≠and␈α≤several␈α≠domain-specific␈α≤BEINGs,␈α≠and
␈↓ ↓H␈↓generalizing␈α"several␈α"parts␈α"of␈α"several␈α"existing␈α"BEINGs.␈α" Since␈α"the
␈↓ ↓H␈↓dialogues␈α⊂for␈α⊂GI␈α⊂and␈α⊂INF␈α⊂were␈α⊂not␈α⊂studied␈α⊂before-hand,␈α⊂their␈α⊂acceptability
␈↓ ↓H␈↓would␈α∪have␈α∪demonstrated␈α∪the␈α∪success␈α∪of␈α∪the␈α∪system.␈α∪ Most␈α∪of␈α∪the␈α∩existing
␈↓ ↓H␈↓BEINGs␈α∀were␈α∀used␈α∀in␈α∀generating␈α∀these␈α∀new␈α∀programs,␈α∀but␈α∀a␈α∀few␈α∀new␈α∀BEINGs
␈↓ ↓H␈↓had␈α⊃to␈α∩be␈α⊃added.␈α∩This␈α⊃addition␈α∩process␈α⊃required␈α∩detailed␈α⊃knowledge␈α∩of␈α⊃the
␈↓ ↓H␈↓PUP6␈α∪system,␈α∪not␈α∪just␈α∀of␈α∪the␈α∪domain.␈α∪ Equally␈α∪discouraging,␈α∀the␈α∪dialogue
␈↓ ↓H␈↓to␈α⊂write␈α⊂INF␈α⊂is␈α⊂too␈α⊂long␈α⊂and␈α⊂detailed␈α⊂for␈α⊂the␈α⊂task␈α⊂at␈α⊂hand.␈α⊂ It␈α⊂also␈α⊂seems
␈↓ ↓H␈↓that␈α↔the␈α↔front␈α⊗end␈α↔is␈α↔too␈α⊗brittle␈α↔to␈α↔allow␈α⊗anyone␈α↔unfamiliar␈α↔with␈α⊗the
␈↓ ↓H␈↓system to easily work with it.

␈↓ ↓H␈↓The␈α∀need␈α∪for␈α∀flexible␈α∪communication␈α∀stems␈α∪only␈α∀partially␈α∀from␈α∪inter-user
␈↓ ↓H␈↓differences.␈α_ A␈α_serious␈α_and␈α_unexpected␈α_source␈α_of␈α_conflict␈α_here␈α_is␈α_the
␈↓ ↓H␈↓amount␈α≥of␈α≥inference␈α≥the␈α≥user␈α≤wants␈α≥done.␈α≥ This␈α≥level␈α≥is␈α≤relatively
␈↓ ↓H␈↓subjective,␈α~and␈α→may␈α~fluctuate␈α~rapidly␈α→even␈α~with␈α→one␈α~user␈α~writing␈α→one
␈↓ ↓H␈↓program.␈α∀Perhaps␈α∀there␈α∪should␈α∀be␈α∀a␈α∪dial␈α∀he␈α∀can␈α∪set.␈α∀At␈α∀one␈α∀extreme,␈α∪the
␈↓ ↓H␈↓system␈α⊃would␈α∩ask␈α⊃the␈α⊃user␈α∩to␈α⊃verify␈α⊃even␈α∩the␈α⊃most␈α⊃trivial␈α∩inductions.␈α⊃ At
␈↓ ↓H␈↓the␈α_other␈α_extreme␈α_setting,␈α_the␈α_system␈α_would␈α_probably␈α_write␈α_the␈α_target
␈↓ ↓H␈↓program␈α∀after␈α∀just␈α∪a␈α∀few␈α∀brief␈α∪user␈α∀inputs.␈α∀The␈α∪user␈α∀would␈α∀then␈α∀try␈α∪out
␈↓ ↓H␈↓one␈α_program␈α_after␈α_another,␈α_interjecting␈α_just␈α_one␈α_or␈α_two␈α_comments␈α_each
␈↓ ↓H␈↓time,␈α∀after␈α∀which␈α∀the␈α∀system␈α∀would␈α∀come␈α∀up␈α∀with␈α∀the␈α∀next␈α∀version.␈α∀ This
␈↓ ↓H␈↓program␈α∩modification␈α∩mode␈α∩seems␈α⊃appropriate␈α∩for␈α∩someone␈α∩ignorant␈α∩of␈α⊃LISP,
␈↓ ↓H␈↓who nevertheless has the I/O behavior of his target clearly in mind.


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 30␈↓ λ⎇THEORY:  CONCLUSIONS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓Some␈α≤of␈α≥the␈α≤BEING␈α≥parts␈α≤proved␈α≥embarrassingly␈α≤unnecessary.␈α≥ The␈α≤CO-
␈↓ ↓H␈↓REQUISITES␈α∀part␈α∀was␈α∀never␈α∀used.␈α∀ The␈α∀only␈α∀activity␈α∀which␈α∀had␈α∀to␈α∀be␈α∀done
␈↓ ↓H␈↓concurrently␈α⊂was␈α⊂demon␈α⊂activation.␈α⊂The␈α⊂AFFECTS␈α⊂part␈α⊂was␈α⊂of␈α⊂interest␈α⊂to␈α⊂the
␈↓ ↓H␈↓user␈α∃occasionally,␈α∃but␈α∃never␈α∃to␈α∀any␈α∃BEING.␈α∃ The␈α∃EFFECTS␈α∃part␈α∀originally
␈↓ ↓H␈↓had␈α⊗a␈α⊗twin,␈α⊗describing␈α⊗what␈α⊗would␈α⊗happen␈α⊗if␈α⊗each␈α⊗BEING␈α⊗were␈α↔␈↓βnot␈↓␈α⊗called
␈↓ ↓H␈↓right␈α∃now.␈α⊗ In␈α∃each␈α∃case,␈α⊗this␈α∃was␈α∃merely␈α⊗a␈α∃trivial␈α∃restatement␈α⊗of␈α∃the
␈↓ ↓H␈↓frame␈α∪problem.␈α∪ So,␈α∪like␈α∀STRIPS␈α∪[Fikes],␈α∪PUP6␈α∪ignores␈α∪the␈α∀frame␈α∪problem:
␈↓ ↓H␈↓all changes must be explicit.

␈↓ ↓H␈↓Much␈α⊂of␈α⊂PUP6's␈α⊂comments␈α⊂are␈α⊂boring␈α⊂and␈α⊂unnecessary;␈α⊂this␈α⊂was␈α⊂felt␈α⊂to␈α⊂be␈α⊂an
␈↓ ↓H␈↓engineering␈α∀problem␈α∃which␈α∀would␈α∀be␈α∃ignored␈α∀in␈α∀all␈α∃but␈α∀a␈α∃"marketable"␈α∀AP
␈↓ ↓H␈↓system.␈α~This␈α~view␈α~was␈α~probably␈α≠incorrect.␈α~One␈α~of␈α~the␈α~most␈α≠severe␈α~AP
␈↓ ↓H␈↓problems␈α⊃is␈α∩having␈α⊃the␈α⊃system␈α∩inform␈α⊃the␈α⊃user␈α∩of␈α⊃precisely␈α⊃what␈α∩he␈α⊃should
␈↓ ↓H␈↓know␈α~--␈α~no␈α~more␈α~nor␈α≠less.␈α~ This␈α~requires␈α~a␈α~sophisticated␈α≠user␈α~model
␈↓ ↓H␈↓cleverly interfaced to the current programming task.

␈↓ ↓H␈↓Another␈α⊗problem␈α⊗with␈α⊗large,␈α⊗long␈α∃dialogues␈α⊗is␈α⊗user␈α⊗error.␈α⊗ A␈α⊗human␈α∃has
␈↓ ↓H␈↓great␈α⊂difficulty␈α⊂keeping␈α⊂"on␈α⊂top"␈α⊂of␈α⊂everything.␈α⊂ He␈α⊂may␈α⊂get␈α⊂lost,␈α⊂forget,
␈↓ ↓H␈↓change␈α↔his␈α↔mind,␈α↔or␈α↔misunderstand.␈α↔ Again,␈α↔this␈α↔problem␈α_was␈α↔originally
␈↓ ↓H␈↓considered␈α_ignorable,␈α_but␈α_has␈α_shown␈α_itself␈α_to␈α_be␈α_a␈α_limiting␈α_practical
␈↓ ↓H␈↓factor␈α⊂in␈α⊂wide␈α⊂accessability.␈α⊂ It␈α⊂was␈α⊂necessary␈α⊂to␈α⊂create␈α⊂a␈α⊂forgetful-user
␈↓ ↓H␈↓demon␈α∀to␈α∪prevent␈α∀anaphoric␈α∪reference␈α∀to␈α∪something␈α∀which,␈α∀though␈α∪uniquely
␈↓ ↓H␈↓determined,␈α hadn't␈α been␈α mentioned␈α within␈α the␈α past␈α several␈α seconds.
␈↓ ↓H␈↓Related␈α∀to␈α∀this␈α∪is␈α∀the␈α∀problem␈α∪of␈α∀keeping␈α∀the␈α∪user␈α∀informed␈α∀of␈α∀where␈α∪he
␈↓ ↓H␈↓is.␈α~PUP6␈α~simulated␈α~a␈α~continuous␈α≠display␈α~of␈α~the␈α~graph␈α~of␈α≠the␈α~current
␈↓ ↓H␈↓partial␈α∩program,␈α⊃augmented␈α∩by␈α∩static␈α⊃and␈α∩dynamic␈α⊃cursors.␈α∩This␈α∩simple␈α⊃use
␈↓ ↓H␈↓of␈α⊗dynamic␈α↔and␈α⊗textual␈α↔indices␈α⊗seems␈α⊗insufficient.␈α↔ The␈α⊗user␈α↔was␈α⊗still
␈↓ ↓H␈↓often␈α∪confused,␈α∪wishing␈α∪a␈α∪section␈α∪referred␈α∪to␈α∪not␈α∪by␈α∪pointing␈α∪but␈α∩rather
␈↓ ↓H␈↓by␈α⊂a␈α⊂brief,␈α⊂meaningful␈α⊂(to␈α⊂him␈α⊂only!)␈α⊂phrase.␈α⊂ This␈α⊂may␈α⊂also␈α⊂be␈α⊂one␈α⊂of␈α⊂the
␈↓ ↓H␈↓major AP problems which must be studied further.

␈↓ ↓H␈↓These␈α∃worries␈α∃about␈α∃large␈α∃dialogues␈α∀arise␈α∃because␈α∃future␈α∃AP␈α∃systems␈α∀are
␈↓ ↓H␈↓viewed␈α⊗as␈α↔tools␈α⊗for␈α↔writing␈α⊗programs␈α⊗which␈α↔humans␈α⊗simply␈α↔cannot␈α⊗manage
␈↓ ↓H␈↓currently:␈α⊂viable␈α⊂natural␈α⊂language␈α⊂systems,␈α⊂huge␈α⊂operating␈α⊂systems,␈α⊂better
␈↓ ↓H␈↓AP systems.

␈↓ ↓H␈↓One␈α∪might␈α∪argue␈α∪against␈α∪ever␈α∪needing␈α∪a␈α∪system␈α∪whose␈α∪target␈α∪programs␈α∩will
␈↓ ↓H␈↓be␈α∃longer␈α∃and␈α∃more␈α∃complex␈α∀than␈α∃the␈α∃system␈α∃itself.␈α∃ First,␈α∀empirically,
␈↓ ↓H␈↓optimizing␈α⊗compilers␈α⊗are␈α⊗viable␈α⊗and␈α∃yet␈α⊗they␈α⊗dwarf␈α⊗almost␈α⊗all␈α⊗the␈α∃code
␈↓ ↓H␈↓they␈α⊂generate.␈α⊂ Second,␈α⊂as␈α⊂the␈α⊂complexity␈α⊂of␈α⊂the␈α⊂transformation␈α⊂increases,
␈↓ ↓H␈↓the␈α∀length␈α∃of␈α∀a␈α∀compiler␈α∃increases␈α∀rapidly.␈α∀ For␈α∃a␈α∀truly␈α∃intelligent␈α∀AP
␈↓ ↓H␈↓system,␈α⊃one␈α∩might␈α⊃be␈α⊃willing␈α∩to␈α⊃tolerate␈α⊃a␈α∩program␈α⊃several␈α⊃times␈α∩as␈α⊃large
␈↓ ↓H␈↓as anything it could produce.

␈↓ ↓H␈↓An␈α~argument␈α~exists␈α~to␈α~counter␈α≠this␈α~one.␈α~ First,␈α~one␈α~might␈α≠object␈α~to
␈↓ ↓H␈↓drawing␈α∩an␈α⊃analogy␈α∩from␈α∩compilers;␈α⊃many␈α∩entities␈α⊃are␈α∩capable␈α∩of␈α⊃producing
␈↓ ↓H␈↓things␈α⊗more␈α⊗sophistocated␈α⊗than␈α⊗themselves,␈α⊗larger␈α⊗than␈α⊗themselves,␈α⊗etc.


␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 31␈↓ λ⎇THEORY:  CONCLUSIONS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓(consider␈α⊃evolution).␈α∩Second,␈α⊃it␈α∩seems␈α⊃that␈α∩there␈α⊃is␈α∩a␈α⊃manageable␈α∩body␈α⊃of
␈↓ ↓H␈↓information␈α∀which␈α∪one␈α∀needs␈α∪master␈α∀to␈α∪do␈α∀programming␈α∀(informal).␈α∪ Viewed
␈↓ ↓H␈↓differently,␈α⊂one␈α⊂can␈α⊂write␈α⊂programs␈α⊂as␈α⊂long␈α⊂as␈α⊂he␈α⊂wishes␈α⊂if␈α⊂the␈α⊂program␈α⊂is
␈↓ ↓H␈↓designed␈α∩in␈α∪a␈α∩clean␈α∪way.␈α∩Thus␈α∪the␈α∩size␈α∪of␈α∩AP␈α∪systems␈α∩will␈α∪probably␈α∩level
␈↓ ↓H␈↓off␈α→(albeit␈α→huge␈α_compared␈α→to␈α→existing␈α→programs)␈α_even␈α→as␈α→the␈α→size␈α_and
␈↓ ↓H␈↓complexity␈α∩of␈α∩their␈α∩generated␈α⊃code␈α∩continues␈α∩to␈α∩increase␈α∩and,␈α⊃eventually,
␈↓ ↓H␈↓surpass␈α⊃them.␈α⊃ Finally,␈α⊃we␈α∩must␈α⊃consider␈α⊃why␈α⊃we␈α∩want␈α⊃a␈α⊃good␈α⊃AP␈α∩system:␈α⊃to
␈↓ ↓H␈↓help␈α∩us␈α⊃write␈α∩large␈α∩programs␈α⊃easily,␈α∩programs␈α⊃which␈α∩might␈α∩be␈α⊃unmanageable
␈↓ ↓H␈↓today.␈α∃ For␈α∃this␈α∃reason␈α∃alone,␈α∃our␈α∃AP␈α∃system␈α∃must␈α∃be␈α∃able␈α∃to␈α∃deal␈α∀with
␈↓ ↓H␈↓programs larger than itself.

␈↓ ↓H␈↓The␈α∪whole␈α∪design␈α∪of␈α∪BEINGs␈α∪is␈α∪oriented␈α∪toward␈α∪this␈α∪large-scale␈α∪end.␈α∩ One
␈↓ ↓H␈↓cannot␈α write␈α tiny,␈α super-efficient␈α programs␈α using␈α BEINGs,␈α any␈α more
␈↓ ↓H␈↓naturally␈α⊃than␈α∩one␈α⊃can␈α∩generate␈α⊃efficient␈α∩machine␈α⊃code␈α∩using␈α⊃a␈α∩high␈α⊃level
␈↓ ↓H␈↓language.␈α⊂A␈α⊂BEINGs␈α⊂system␈α⊂might␈α⊂simulate␈α⊂this␈α⊂activity,␈α⊂but␈α⊂it␈α⊂would␈α⊂be␈α⊂as
␈↓ ↓H␈↓awkward␈α~and␈α~opaque␈α~as␈α~if␈α≠they␈α~were␈α~asked␈α~to␈α~simulate␈α≠volleyball.␈α~By
␈↓ ↓H␈↓relinquishing␈α∩more␈α∩and␈α∩more␈α⊃control␈α∩to␈α∩the␈α∩computer␈α∩language␈α⊃environment,
␈↓ ↓H␈↓the␈α⊗programmer␈α↔sacrifices␈α⊗specialization␈α↔of␈α⊗the␈α⊗final␈α↔code␈α⊗for␈α↔ease␈α⊗of
␈↓ ↓H␈↓constructing it and for its greater size and complexity.






























␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 32␈↓ λ⎇THEORY:  CONCLUSIONS
␈↓ ↓H␈↓␈↓αBEINGS␈↓␈↓ 	U␈↓βDoug Lenat␈↓


␈↓ ↓H␈↓␈↓↓9. ACKNOWLEDGEMENTS␈↓

␈↓ ↓H␈↓There␈α∃are,␈α∃of␈α∃course,␈α∃countless␈α∀ideas␈α∃embodied␈α∃in␈α∃any␈α∃concrete␈α∀project.
␈↓ ↓H␈↓Sweeping␈α∪philosophical␈α∪assumptions␈α∪are␈α∀made␈α∪simply␈α∪by␈α∪deciding␈α∪to␈α∀do␈α∪any
␈↓ ↓H␈↓type␈α⊗of␈α⊗programming␈α⊗[McCarthy],␈α⊗even␈α⊗moreso␈α⊗with␈α⊗Automatic␈α⊗Programming.
␈↓ ↓H␈↓Any␈α⊂Program-Understanding␈α⊂Program␈α⊂should␈α⊂include␈α⊂the␈α⊂best␈α⊂parts␈α⊂of␈α⊂all␈α⊂the
␈↓ ↓H␈↓best␈α⊗old␈α↔ideas.␈α⊗ PUP6␈α↔relies␈α⊗on␈α⊗concepts␈α↔gleaned␈α⊗from␈α↔Actors␈α⊗[Hewitt],
␈↓ ↓H␈↓Demons␈α∪[........],␈α∪heterarchy␈α∩[.....],␈α∪structured␈α∪programming␈α∩[Dijkstra],
␈↓ ↓H␈↓assertional␈α≡data␈α≡bases␈α≡and␈α≡flexible␈α≡data␈α≡types␈α≡[Rulifson],␈α≡pattern-
␈↓ ↓H␈↓directed␈α⊂invocation␈α⊂of␈α⊂procedural␈α⊂knowledge␈α⊂[........],␈α⊂the␈α⊂paradigm␈α⊂of␈α⊂AP
␈↓ ↓H␈↓by␈α≤dialogue␈α≤[Floyd],␈α≤and␈α≤studies␈α≤on␈α≤program␈α≤specification␈α≤techniques
␈↓ ↓H␈↓[Green].␈α≠ Of␈α≠course␈α~this␈α≠list␈α≠is␈α~incomplete;␈α≠sophisticated␈α≠ideas␈α~are
␈↓ ↓H␈↓captured␈α+in␈α,the␈α+languages␈α,themselves:␈α+QLISP␈α,[Reboh],␈α+INTERLISP
␈↓ ↓H␈↓[Teitelman],␈α≤LISP␈α≤[McCarthy2],␈α≤and␈α≤English␈α≤[Anonymous].␈α≤To␈α≤this␈α≤rich
␈↓ ↓H␈↓store, one may achieve new heights merely by synergy.

␈↓ ↓H␈↓Any␈α∪success␈α∪of␈α∩the␈α∪BEINGs␈α∪project,␈α∩as␈α∪well␈α∪as␈α∩the␈α∪precursor␈α∪PUP␈α∩programs
␈↓ ↓H␈↓[Green]␈α↔is␈α↔due␈α⊗in␈α↔large␈α↔measure␈α⊗to␈α↔the␈α↔creative␈α⊗energy␈α↔of␈α↔C.␈α⊗ Cordell
␈↓ ↓H␈↓Green.␈α⊂ I␈α⊂have␈α⊂also␈α⊂drawn␈α⊂upon␈α⊂discussions␈α⊂with␈α⊂D.␈α⊂Barstow,␈α⊂B.␈α⊂ McCune,␈α⊂D.
␈↓ ↓H␈↓Shaw,␈α∩E.␈α⊃ Sacerdoti,␈α∩L.␈α∩ Steinberg,␈α⊃and␈α∩R.␈α⊃ Waldinger.␈α∩ The␈α∩generosity␈α⊃of
␈↓ ↓H␈↓SRI,␈α∩in␈α⊃providing␈α∩computer␈α∩time␈α⊃and␈α∩language␈α⊃consultations,␈α∩should␈α∩not␈α⊃go
␈↓ ↓H␈↓unmentioned.␈α⊂ Also␈α⊂valuable␈α⊂were␈α⊂the␈α⊂critical␈α⊂readings␈α⊂of␈α⊂this␈α⊂paper␈α⊂by␈α⊂R.
␈↓ ↓H␈↓Davis and T. Winograd.


























␈↓ ↓H␈↓␈↓∧Fourth Draft .... November 11, 1974␈α?␈α?␈α?␈α?␈α⊃page 33␈↓ 
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