copyright © 2002 cycorp writing efficient cycl: part 2 part one: general suggestions –simpler is...

Copyright © 2002 Cycorp

Writing Efficient CycL: Part 2

• Part One: General Suggestions– Simpler is Better

– Use Rule Macro Predicates

– Create Simplifying Vocabulary

• Part Two: Cyc-Specific Suggestions– Factor out Commonality

– Existence is Expensive

– Exceptions are Exceptional

– State Negations Explicitly

– Generalize -- Don’t List– Use #$different



• Factor out Commonality• Existence is Expensive• Exceptions are Exceptional• State Negations Explicitly• Generalize -- Don’t List• Use #$different


N*M reduces to N+M

When similarity is not a coincidenceN*M reduces to N+M

A B C D

W X Y Z

P

A B C D

W X Y Z


Commonalities in Collections

Olympic Men’s Individual 400 Meter Butterfly

Olympic Women’sIndividual 100 Meter Backstroke

Olympic Women’s Individual 200 MeterFreestyle

Olympic Men’s Individual 200 MeterBackstroke



Olympic Competition

Individual Competition

Swimming Competition







Olympic Competition

Individual Competition

Swimming Competition





Olympic Individual Swimming


Commonalities in Microtheories

April 15, 2002 USA Today

Sports SectionMt

June 2, 2002 USA Today

Sports SectionMt

October 8, 2002 USA Today

Sports SectionMt

September 21, 2002 USA Today

Sports SectionMt

............



Rules forGames Mt

American SportsCompetition Mt

Current and Historical Stats Mt


Sports SectionMt


Sports SectionMt


Sports SectionMt


Sports SectionMt




Sports SectionMt


Sports SectionMt


Sports SectionMt


Sports SectionMt

Rules forGames Mt





Rules, Competition, and Stats Mt


Sports SectionMt


Sports SectionMt


Sports SectionMt


Sports SectionMt

Rules forGames Mt




Microtheories + a Forward RuleX Y T

A

Z

PQRS

S

P Q R


Microtheories + a Forward Rule

X Y TZ

PQRS

C

S

D

S

A

S

B

S ...

P Q R


T

PQRS

...

S Shared Assumptions Mt

Microtheories + a Forward Rule

X Y Z

C DA B

P Q R


Concluding #$thereExists

• Skolemization– In order to conclude #$thereExists,

introduce a function to denote the thing that so exists so that we can reason with it

– Extends the number of concepts and symbols in the language that the system might have to think about

– Things that conclude #$thereExists are a little more expensive than others


State Existence Generally• Pervasive problem

Every elephant has a headEvery elephant has a head with a trunkEvery cat has a head with whiskersEvery spotted wombat has a spotted head…

• State existence generally, constrain specificallyEvery animal has a headEvery elephant has a trunkAn animal’s trunk is part of its head


Overuse of #$not(#$implies (#$and (#$isa ?BRD #$Bird) (#$not (#$isa ?BRD #$Penguin)))(#$behaviorCapableOf ?BRD #$Flying #$performedBy))

What about Emus?

What about these examples?– broken wings– feet in concrete– slathered in crude oil– hypnotized into thinking it is a dog


Use Default ReasoningSolution : use default reasoning(#$implies (#$isa ?BRD #$Bird) (#$behaviorCapableOf ?BRD #$Flying #$performedBy))

(#$exceptWhen (#$isa ?BRD #$FlightlessBird) (#$implies (#$isa ?BRD #$Bird) (#$behaviorCapableOf ?BRD #$Flying

#$performedBy)))

(#$genls #$Penguin #$FlightlessBird)(#$genls #$Emu #$FlightlessBird)...


Postpone Checking for Exceptions

• Save a lot of work– only check for exceptional cases after using the

rule

• #$not’s in the antecedent of a rule you’re writing?– ask yourself “is this what the rule really means

or this a meta-statement about cases where that rule wouldn’t apply and should be stated as an exception?”


Underuse of #$not

• Better to conclude than assume• Negations can prune inferences• Some Powerful Negations

• #$disjointWith

is not a (#$disjointWith)


Powerful Negations

• #$SiblingDisjointCollection

• #$completeExtentKnown

is not a (#$SiblingDisjointCollection)

is not a (#$SiblingDisjointCollection)

(#$completeExtentKnown #$nationalBorder)


Another Powerful Negation

• #$completeCollectionExtent

(#$completeCollectionExtent #$MonthOfYearType)

#$January, #$February, #$March, #$April, #$May, #$June, #$July, #$August, #$September, #$October, #$November, #$December

+ #$Yule ?


Disjunctions? Try to Generalize

• “list-em” KR is almost always wrong

(#$implies (#$and (#$isa ?PRSN #$Person) (#$or (#$brothers ?PRSN ?SBLNG) (#$sisters ?PRSN ?SBLNG)))(#$feelsTowardsObject ?PRSN ?SBLNG #$Rivalry

#$Positive))

• Create vocabulary for the generalization#$siblings


Use #$different

Avoid (#$not (#$equals ...))

(#$different <ITEM-1> <ITEM-2> <ITEM-3> ...)

is much better than

(#$and (#$not (#$equals <ITEM-1> <ITEM-2>))

(#$not (#$equals <ITEM-1> <ITEM-3>)) (#$not (#$equals <ITEM-2> <ITEM-3>))

...)


Summary

• Factor out Commonality• Existence is Expensive• Exceptions are Exceptional• State Negations Explicitly• Generalize - Don’t List• Use #$different

Avoid (#$not (#$equals ...))

copyright © 2002 cycorp writing efficient cycl: part 2 part one: general suggestions –simpler is...

Documents

sports section mt slide

sports section mt rules

meter backstroke slide

historical stats mt

cycorp commonalities

cycorp microtheories

cycorp n

different slide