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
shapiro@cse.buffalo.edu
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.
S.C. Shapiro
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
S.C. Shapiro
Outline
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Introduction
Intensional Entities
Complex Categories
Possession I
Propositions about Propositions
Possession II
Summary
S.C. Shapiro
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.
S.C. Shapiro
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.
S.C. Shapiro
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.
S.C. Shapiro
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.
S.C. Shapiro
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
S.C. Shapiro
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.
S.C. Shapiro
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.
S.C. Shapiro
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.
S.C. Shapiro
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.
S.C. Shapiro
PseudoRepresentation of
Complex Categories
• Isa(B30, CompCat(orange, CompCat(juice, seat)))
• Isa(Pat, CompCat(excellent, teacher))
• Isa(Lucy, CompCat(former, teacher))
S.C. Shapiro
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.”
S.C. Shapiro
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.
S.C. Shapiro
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.
S.C. Shapiro
PseudoRepresentation of
Possession
• Has(Richard, meat, B35)
• Has(Henry, poison, B37)
• Equiv(B35, B37)
S.C. Shapiro
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.
S.C. Shapiro
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.
S.C. Shapiro
Representing Propositions
• Representation of Proposition
– Not by a Logical Sentence
– But by a Functional Term
– Denoting a Proposition.
S.C. Shapiro
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)
S.C. Shapiro
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.
S.C. Shapiro
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.
S.C. Shapiro
Possession II.3
: What is an inalienable possession?
I don't know.
: What is an alienable possession?
I don't know.
S.C. Shapiro
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.
S.C. Shapiro
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.
S.C. Shapiro
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))
S.C. Shapiro
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