Transcript Knowledge Representation for Natural Language Competence

Knowledge Representation for
Natural Language Competence
Stuart C. Shapiro
Department of Computer Science and Engineering
and Center for Cognitive Science
State University of New York at Buffalo
[email protected]
S.C. Shapiro
Motivation
• Deep understanding of NL texts requires a
Knowledge Representation & Reasoning
formalism/system.
• A variety of logic.
• But not the logic for metamathematics.
S.C. Shapiro
Preview
• I will discuss several issues in KRR for NL
Competence,
• Illustrated by interactions with a computational
agent.
• Agent: Cassie.
• KRR system: SNePS.
• Interactions are transcribed from consecutive
interactions in a single session.
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Interaction with Cassie
English
(Statement, Question, Command)
(New Belief)
[SNePS]
(Current) Set of Beliefs
[SNePS]
Reasoning
Clarification Dialogue
GATN Parser
Looking in World
Answer
Actions (Updated) Set
of Beliefs
[SNIP]
[SNeRE]
[SNePS]
GATN
Generator
Reasoning
English sentence expressing
new belief answering question reporting actions
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Outline
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Introduction
Intensional Entities
Complex Categories
Possession I
Propositions about Propositions
Possession II
Summary
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Intensional Entities 1
• Rather than represent “objects in the world,”
represent mental entities.
• Includes Imaginary and Fictional Entities.
• Multiple mental entities may correspond to
one world object.
– Intensional entities may be co-extensional.
– But must be kept separate.
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Intensional Entities 2
: The morning star is the evening star.
I understand that the morning star is the evening
star.
: The evening star is Venus.
I understand that Venus is the evening star.
: Clark Kent is Superman.
I understand that Superman is Clark Kent.
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Intensional Entities 3
: Lois Lane saw Clark Kent.
I understand that Lois Lane saw Clark Kent.
: Did Lois Lane see Superman?
I don't know.
: Did Lois Lane see Clark Kent?
Yes, Lois Lane saw Clark Kent.
Note Open World Assumption.
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Intensional Entities 4
: Superman went to the morning star.
I understand that Superman went to Venus.
: Did Clark Kent go to Venus?
Yes, Superman went to Venus.
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Intensional Entities 5
: Buck Rogers went to the evening star.
I understand that Buck Rogers went to Venus.
: Who went to Venus?
Buck Rogers went to Venus
and Superman went to Venus.
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Intensional Entities 6
The morning star
The evening star
Go to
Go to
Superman
Clark Kent
See
Lois Lane
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Venus
Buck Rogers
Outline
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S.C. Shapiro
Introduction
Intensional Entities
Complex Categories
Possession I
Propositions about Propositions
Possession II
Summary
Complex Categories 1
• Noun Phrases:
<Det> {N | Adj}* N
Understanding of the modification must
be left to reasoning.
Example:
orange juice seat
Representation must be left vague.
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Complex Categories 2
: Kevin went to the orange juice seat.
I understand that Kevin went to the orange juice
seat.
: Did Kevin go to a seat?
Yes, Kevin went to the orange juice seat.
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Complex Categories 3
: Pat is an excellent teacher.
I understand that Pat is an excellent teacher.
: Is Pat a teacher?
Yes, Pat is a teacher.
: Lucy is a former teacher.
I understand that Lucy is a former teacher.
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Complex Categories 4
: `former' is a negative adjective.
I understand that `former' is a negative adjective.
: Is Lucy a teacher?
No, Lucy is not a teacher.
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PseudoRepresentation of
Complex Categories
• Isa(B30, CompCat(orange, CompCat(juice, seat)))
• Isa(Pat, CompCat(excellent, teacher))
• Isa(Lucy, CompCat(former, teacher))
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Outline
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S.C. Shapiro
Introduction
Intensional Entities
Complex Categories
Possession I
Propositions about Propositions
Possession II
Summary
Possession I.1
• “One man’s meat is another man’s poison.”
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Possession I.2
: Richard's meat is Henry's poison.
I understand that Henry's poison is Richard's
meat.
: Edward ate Richard's meat.
I understand that Edward ate Richard's meat.
: Did Edward eat Henry's poison?
Yes, Edward ate Henry's poison.
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Possession I.3
: Did Edward eat Henry’s meat?
I don’t know.
: Did Edward eat Richard's poison?
I don’t know.
Moral: Possession is a three-place relation.
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PseudoRepresentation of
Possession
• Has(Richard, meat, B35)
• Has(Henry, poison, B37)
• Equiv(B35, B37)
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Outline
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S.C. Shapiro
Introduction
Intensional Entities
Complex Categories
Possession I
Propositions about Propositions
Possession II
Summary
Propositions about Propositions 1
• Propositions are “first-class” mental entities.
• They can be discussed, just like other mental
entities.
• And must be represented like other mental
entities.
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Propositions about Propositions 2
: That Bill is sweet is Mary's favorite proposition.
I understand that Mary's favorite proposition is
that Bill is sweet.
: Mike believes Mary's favorite proposition.
I understand that Mike believes that Bill is sweet.
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Propositions about Propositions 3
: That Mary's favorite proposition is that Bill is
sweet is cute.
I understand that that Mary's favorite proposition
is that Bill is sweet is cute.
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Representing Propositions
• Representation of Proposition
– Not by a Logical Sentence
– But by a Functional Term
– Denoting a Proposition.
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PseudoRepresentation of
Propositions about Propositions
• Has(Mary, CompCat(favorite, proposition),
HasProp(Bill, sweet))
• Believes(Mike, HasProp(Bill, sweet))
• HasProp(Has(Mary,
CompCat(favorite, proposition),
HasProp(Bill, sweet)),
cute)
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Outline
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S.C. Shapiro
Introduction
Intensional Entities
Complex Categories
Possession I
Propositions about Propositions
Possession II
Summary
Possession II.1
• Examples from J. Lyons, Semantics I, 1977,
p. 312,
• of inalienable possessive constructions:
“John’s right arm”
• of alienable possessive constructions:
“John’s book”
• Use vague representation
with later reasoning.
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Possession II.2
: Caren held Stu's hand.
I understand that Caren held Stu's hand.
: Mary held Bill's book.
I understand that Mary held Bill's book.
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Possession II.3
: What is an inalienable possession?
I don't know.
: What is an alienable possession?
I don't know.
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Possession II.4
: Hands are body parts.
I understand that hands are body parts.
: Books are ownable objects.
I understand that books are ownable objects.
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Possession II.5
: What is Stu's hand?
Stu’s hand is the hand.
: What is Bill's book?
Bill’s book is the book.
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Possession II.6
: What is an inalienable possession?
That Stu has a hand is the inalienable possession.
: What is an alienable possession?
That Bill has a book is the alienable possession.
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PseudoRepresentation of
Possession
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Has(Stu, hand, B47)
Has(Bill, book, B49)
Held(Caren, B47)
Held(Mary, B49)
Isa(Has(Stu, hand, B47),
CompCat(inalienable, possession))
• Isa(Has(Bill, book, B49),
CompCat(alienable, possession))
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Outline
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S.C. Shapiro
Introduction
Intensional Entities
Complex Categories
Possession I
Propositions about Propositions
Possession II
Summary
Summary
• Represent intensional (mental) entities.
• Open World Assumption
• Vague representation of complex categories.
– Clarified by reasoning.
• Ability to discuss words.
– NL is its own metalanguage.
• Possession as a three-place relation.
• Propositions as first-class entities.
• Vague representation of possession.
– Clarified by reasoning.
• Supplying taxonomy via NL inputs.
S.C. Shapiro
SNePS Research Group
Current Members
• Faculty:
Stuart C. Shapiro, Director
William J. Rapaport, Associate Director
Carl Alphonce
Jean-Pierre A. Koenig
David R. Pierce
• Graduate Students:
Marc Broklawski
Debra T. Burhans
Frances L. Johnson
S.C. Shapiro
Bharat Bhushan
Haythem O. Ismail
John F. Santore
For More Information
• URL: http://www.cse.buffalo.edu/~shapiro/
• Group: http://www.cse.buffalo.edu/sneps/
S.C. Shapiro