COMMENT ⊗   VALID 00015 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	This presentation will be 2 distinct,
C00003 00003				      MYCIN SCENARIO
C00004 00004			Narrow down to those of KE approach
C00005 00005		DEC's activities
C00007 00006		In general, some proof procedure.
C00008 00007		* Modus Monens
C00009 00008		Extendability
C00010 00009	System can explain reasoning -
C00011 00010		SIMPLIFICATIONS
C00012 00011	MYCIN is interactive
C00013 00012	End of Part I.
C00014 00013		   [[[	LEAVE DISPLAYED ]]]
C00015 00014	Automating KA 
C00016 00015	1. Gross characteristics
C00017 ENDMK
C⊗;
This presentation will be 2 distinct,
but interconnected, talks.

Expert Systems --
	What they are
	Why worth studying
	How they work (coarse)

When more?
Once central bottleneck -- Knowledge Acquisition -- solved.
(That is 2nd part)

-----
Meta Point -
	Ask Questions!
	Esp if too slow, or too fast
			      MYCIN SCENARIO

Begin talk w/story
	[turn off projector]

General Practioner
  examines patient,
  sees possible meningitus
  calls infectuous disease expert

Ensuing dialogue,
  mixed initiative
  unknowns - (spinal tap) test not run
  uncertain - how high fever really is

GP can challenge -- 
  why did you ask this?
  how did you conclude that?

Diagnosis
  - organisms responsible

Treatment
  - to cover all remaining cases
  - complete with caveats

----
Happily ever after

		Narrow down to those of KE approach

(Report by Buchanan & Duda)

 - judgmental (w/ formal justification)

 - explain conclusions; justify results

 - modify; incremental input


-------

Onto structural description 
	- internals needed for ↑
	DEC's activities

As DEC users forum

As example of how big company ...
(IBM, TI, ... have similar story)

 (From talk by S Polit,  26/Oct/82)

XCON in use
  For misc DEC machines
  Determines what else to be ordered
	     whether can be filled, w/in constraint
	     explains additional facts -- what is missed, why, ...
  Gives assembly instructions

XSEL in use
  - Interactive
  - Its output to XCON

XSITE
  - Room layout to physical layout

ISA
  - when full system will be ready

-----
Sizer 
  - by Phil London
  - to minimize energy

Layout Tool
  - to fit components on chips, efficiently


-----
First Principles Reasoner
  - w/ Randy Davis
  -	Structural descrption
	Behaviour  [Electrical vs Inference]
	Principle of Violated Expectation
	Explicit Fault Model
	In general, some proof procedure.
Simple one: Backward Chaining

Here is simple case

(overly simplified --
 we'll discuss deficiencies at end)

	* Modus Monens

To prove B
  Given A =>B,
  Simply proof A

Notation - AND , OR


----
Easy to use these "chunks" for explanation
 why/how conclusion reached
	Extendability

* NOT simply decision tree
	- no where explicit -- just drawn for pedagogy

* New branches
	- added by simple FACTS RE: WORLD  (rule)
	- not hardwired;
	  no need to describe how it relates to world -- fits itself



* This rule applicable anyway you need to acquire $$.

System can explain reasoning -
 how conclusion reached

Show subgoals achieved, and rules used

(This simple example only for pedagogic)
	SIMPLIFICATIONS

SEARCH

Only One Direction of Search --
	(Could be Forward, as wel as Backward)
	[Dictated by topology of search spae - meta-level issues]

(Order of instantiation)
∃ many goals on "frontier";
   Which goal to expand next?
	If wrong, could lead BACKTRACK
		  or to ∞ descent.
   Focus of Attention (esp when interactive)


-----
VARIABLES -- many things abstractable 
  Fred -> person

-----
Interaction
Focus of Att'n -
	could give all facts re: x first -- or not
HUMAN ENGINEERING
Q/Aing, ...
MYCIN is interactive

User can ask why Mycin asked <x>.
or how conclusion reached


----

Easy to credit/blame a specific rule
	- & fix system by changing rule, if appropriate!
(This tool solves large class of errors)
because RULES ARE MODULAR!
End of Part I.

Note complex rule?

Q: How did it get here?

A: KA! == topic of Part II
	   [[[	LEAVE DISPLAYED ]]]

Facts re: world -> expert -> KB

which KB uses to solve problem.

Why going so poorly?
This brings up most of problems w/ESs in general.

This is major research issue, @ S, etc.

"central bottleneck in ES construction"
Automating KA 
 - first by person as interface,
 - gradually remove him from loop

1.1 Think in English, but talk in Lisp
  Or Spatially, but type in sequentially

2.1 We know re: rules, blackboard models, predicate calculus

[Like Malinowski: If All have = hammer, all world looks like a nail.]

1. Gross characteristics
	Classes
	Relevant Properties

2. Fleshing out
	[New instances]

3. Refinements
	[Small twiddles, minor rearrangements]

----

E.g. Facts re: Organisms

Longevity
Host
Type - Viral, Bacterial, Fungal, ...