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␈↓ α←␈↓	␈↓ ∧8Acknowledgements







␈↓ α←␈↓This␈αbook␈αbegan␈αinformally␈α
at␈αUCLA␈αin␈α1970␈α
as␈αan␈αalternative␈αto␈α
the␈αdata
␈↓ α←␈↓structures␈αcourse.␈αAny␈αbook␈αwhich␈αtakes␈αeight␈αyears␈αto␈αcomplete␈αmust␈αhave␈αa
␈↓ α←␈↓list␈α⊂of␈α⊂acknowledgements.␈α∂ Between␈α⊂ the␈α⊂1970␈α∂manuscript␈α⊂and␈α⊂the␈α∂ present
␈↓ α←␈↓version␈α
stretches␈αan␈α
incredible␈α
list␈αof␈α
revisions␈α
and␈αrewritings.␈α
 That␈αtask␈α
was
␈↓ α←␈↓made␈α∩possible␈α∩only␈α∩by␈α∩the␈α∩document␈α∩preparation␈α∩system␈α∩at␈α∩the␈α⊃Stanford
␈↓ α←␈↓Artificial␈α∂Intelligence␈α∂Laboratory.␈α⊂ The␈α∂Artificial␈α∂Intelligence␈α⊂community␈α∂is
␈↓ α←␈↓still the superior developer of computer related tools.

␈↓ α←␈↓␈↓ β'The␈α∂final␈α∂shape␈α∂of␈α∂this␈α∂book␈α∂has␈α∂been␈α∂guided␈α∂by␈α∂many␈α∂sources,␈α∞but
␈↓ α←␈↓particularly␈αI␈αwould␈αlike␈αto␈αmention␈α Michael␈αBurke␈αand␈α the␈αSan␈αJose␈αState
␈↓ α←␈↓Mathematics␈α⊃Department,␈α⊂who␈α⊃allowed␈α⊂me␈α⊃to␈α⊂use␈α⊃my␈α⊂manuscript␈α⊃in␈α⊂their
␈↓ α←␈↓data␈α∂structures␈α∂course.␈α∂ To␈α⊂Nancy␈α∂Meller␈α∂of␈α∂the␈α∂UCLA␈α⊂Computer␈α∂Science
␈↓ α←␈↓Department␈α∪for␈α∪typing␈α∀the␈α∪orginal␈α∪LISP␈α∪notes.␈α∀ To␈α∪Les␈α∪Earnest␈α∀of␈α∪the
␈↓ α←␈↓Stanford␈αA.I.␈αLabs␈αfor␈α
aid␈αbeyond␈αthe␈αcall␈αof␈α
duty.␈α To␈αPaulette␈αfor␈αtrying␈α
to
␈↓ α←␈↓understand.␈α
To␈α
Richard␈α
Manuck␈αof␈α
the␈α
Stanford␈α
Computer␈αScience␈α
 Library,
␈↓ α←␈↓a␈α∞most␈α∞excellent␈α∞librarian␈α∞with␈α∞an␈α∞exceptional␈α∞library.␈α∞ To␈α∞John␈α
McCarthy
␈↓ α←␈↓for␈α the␈αinsight␈α which␈αled␈αto␈αLISP,␈αand␈α for␈αestablishing␈αan␈αenvironment␈αat
␈↓ α←␈↓Stanford␈αwhich␈αis␈α staffed␈αso␈αadmirably␈αand␈αsupplied␈αwith␈αso␈αmany␈αtalented
␈↓ α←␈↓people.␈α∂ To␈α∞E,␈α∂PUB,␈α∂and␈α∞the␈α∂XGP,␈α∞for␈α∂existing.␈α∂ To␈α∞Dick␈α∂Dolan␈α∂and␈α∞the
␈↓ α←␈↓staff␈α⊂of␈α⊂the␈α⊂H-P␈α⊂Journal,␈α⊃who␈α⊂ both␈α⊂tolerated␈α⊂and␈α⊂ sympathized␈α⊃with␈α⊂my
␈↓ α←␈↓attempts␈α⊃to␈α⊃transform␈α⊃ the␈α⊂computer␈α⊃generated␈α⊃text␈α⊃into␈α⊃something␈α⊂which
␈↓ α←␈↓could be typeset.


␈↓ α←␈↓␈↓ β'Particular␈α
mention␈αmust␈α
go␈α
to␈α Guy␈α
Steele␈αand␈α
Gianfranco␈α
Prini.␈αGuy
␈↓ α←␈↓reviewed␈α∞a␈α∂much␈α∞inferior␈α∞version␈α∂of␈α∞this␈α∞text.␈α∂His␈α∞insights,␈α∂comments,␈α∞and
␈↓ α←␈↓criticisms␈αwere␈α invaluable.␈α
With␈αcomments␈αlike:␈α
"that's␈αnot␈αa␈αcompromise,␈α
it's
␈↓ α←␈↓a␈α
bloody␈α
surrender!",␈α
the␈α
text␈αwas␈α
bound␈α
to␈α
improve.␈α
Gianfranco,␈α
was␈αmore
␈↓ α←␈↓fortunate;␈α
he␈α
reviewed␈α
the␈α
results␈α
of␈α
Guy's␈α
scoldings.␈α
Many␈α
other␈α
people␈α
have
␈↓ α←␈↓had␈α⊗significant␈α⊗influence␈α⊗on␈α⊗the␈α↔text.␈α⊗I␈α⊗feel␈α⊗fortunate␈α⊗to␈α⊗ be␈α↔able␈α⊗to
␈↓ α←␈↓acknowledge␈αthese␈αindividuals:␈αBruce␈αAnderson,␈αBob␈αBoyer,␈αMichael␈αClancy,
␈↓ α←␈↓Bob␈α⊃Doran,␈α⊃Daniel␈α∩Friedman,␈α⊃Richard␈α⊃Gabriel,␈α⊃Michael␈α∩Gordon,␈α⊃Patrick
␈↓ α←␈↓Greussay,␈α_Anthony␈α_Hearn,␈α↔Freidrich␈α_von Henke,␈α_Forrest␈α_Howard,␈α↔Bill
␈↓ α←␈↓McKeeman,␈αPeter␈αMilne,␈αJ S.␈α
Moore,␈αJorge␈αMorales,␈αCharles␈α
Prenner,␈αSteve
␈↓ α←␈↓Russell,␈α⊂Hanan␈α⊂Samet,␈α⊂Vic␈α∂Scheinman,␈α⊂Herbert␈α⊂Stoyan,␈α⊂Dennis␈α⊂Ting,␈α∂and
␈↓ α←␈↓Steve␈α∂Ward.␈α∂I␈α∂apologize␈α∞to␈α∂any␈α∂individuals␈α∂I␈α∞neglected␈α∂to␈α∂mention;␈α∂I␈α∞must
␈↓ α←␈↓surely have forgotten someone.

␈↓ α←␈↓␈↓ β'Similarly␈α
there␈αare␈α
topics␈α
 related␈αto␈α
LISP␈α
which␈αI␈α
have␈αneglected.␈α
 The
␈↓ α←␈↓whole␈α∞area␈α∂of␈α∞Artificial␈α∂Intelligence␈α∞applications␈α∞has␈α∂been␈α∞slighted,␈α∂but␈α∞for
␈↓ α←␈↓every␈α
author␈α∞there␈α
must␈α
come␈α∞a␈α
time␈α∞when␈α
you␈α
have␈α∞to␈α
say␈α∞"Enough!"␈α
I've
␈↓ α←␈↓been␈α
saying␈α∞that␈α
for␈α
several␈α∞years.␈α
It␈α
is␈α∞particularly␈α
difficult␈α
to␈α∞ cease␈α
when
␈↓ α←␈↓dealing␈αwith␈αa␈αtopic␈αas␈α dynamic␈αas␈αLISP.␈αMany␈αsections␈αonly␈αhint␈αat␈αdeeper
␈↓ α←␈↓problems, and surely some errors persist; but "Enough!"

␈↓ α←␈↓␈↓ β'As␈α⊃always,␈α⊃it␈α⊃is␈α⊃the␈α∩author's␈α⊃responsibility␈α⊃for␈α⊃the␈α⊃final␈α⊃shape␈α∩of␈α⊃a
␈↓ α←␈↓document;␈α→the␈α_substantial␈α→and␈α_textual␈α→errors,␈α_errors␈α→of␈α→omission␈α_and
␈↓ α←␈↓commission␈α∞are␈α∞all␈α∞mine.␈α
Each␈α∞of␈α∞the␈α∞reviewers␈α
objected␈α∞strongly␈α∞to␈α∞one␈α
or
␈↓ α←␈↓more␈α∪facets␈α∪of␈α∪this␈α∪book;␈α∪to␈α∀some,␈α∪it␈α∪was␈α∪too␈α∪theoretical;␈α∪for␈α∀some,␈α∪too
␈↓ α←␈↓practical.  I must have done something right.












␈↓ α←␈↓α␈↓ ∧CTo my parents, John & Esther Allen
␈↓ α←␈↓α␈↓ ∧C␈↓ ¬;To my friend and wife, Ruth E. Davis
␈↓ α←␈↓α␈↓ ∧C␈↓ ¬;␈↓ ε3To my sons, Christopher & Geoffrey.