cse@buffalo s.c. shapiro knowledge representation for natural language competence stuart c. shapiro...
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S.C. Shapiro
cse@buff
alo
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
S.C. Shapiro
cse@buff
alo
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
cse@buff
alo
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
cse@buff
alo
Interaction with CassieEnglish
(Statement, Question, Command)
(Current) Set of Beliefs[SNePS]
(Updated) Setof Beliefs[SNePS]
Actions[SNeRE]
(New Belief)[SNePS]
English sentence expressingnew belief answering question reporting actions
Answer[SNIP]
GATN Parser
GATN Generator
ReasoningClarification DialogueLooking in World
Reasoning
S.C. Shapiro
cse@buff
alo
Outline
• Introduction
• Intensional Entities
• Complex Categories
• Possession I
• Propositions about Propositions
• Possession II
• Summary
S.C. Shapiro
cse@buff
alo
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
cse@buff
alo
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
cse@buff
alo
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
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alo
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
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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.
S.C. Shapiro
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Intensional Entities 6
The morning star The evening star Venus
Superman Clark Kent Buck Rogers
Lois Lane
Go toGo to
See
S.C. Shapiro
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alo
Outline
• Introduction
• Intensional Entities
• Complex Categories
• Possession I
• Propositions about Propositions
• Possession II
• Summary
S.C. Shapiro
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alo
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
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: 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.
Complex Categories 2
S.C. Shapiro
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: 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.
Complex Categories 3
S.C. Shapiro
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: `former' is a negative adjective.
I understand that `former' is a negative adjective.
: Is Lucy a teacher?
No, Lucy is not a teacher.
Complex Categories 4
S.C. Shapiro
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alo
PseudoRepresentation of Complex Categories
• Isa(B30, CompCat(orange, CompCat(juice, seat)))
• Isa(Pat, CompCat(excellent, teacher))
• Isa(Lucy, CompCat(former, teacher))
S.C. Shapiro
cse@buff
alo
Outline
• Introduction
• Intensional Entities
• Complex Categories
• Possession I
• Propositions about Propositions
• Possession II
• Summary
S.C. Shapiro
cse@buff
alo
: 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.
Possession I.2
S.C. Shapiro
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: Did Edward eat Henry’s meat? I don’t know.
: Did Edward eat Richard's poison? I don’t know.
Possession I.3
Moral: Possession is a three-place relation.
S.C. Shapiro
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PseudoRepresentation of Possession
• Has(Richard, meat, B35)
• Has(Henry, poison, B37)
• Equiv(B35, B37)
S.C. Shapiro
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alo
Outline
• Introduction
• Intensional Entities
• Complex Categories
• Possession I
• Propositions about Propositions
• Possession II
• Summary
S.C. Shapiro
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alo
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
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: 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.
Propositions about Propositions 2
S.C. Shapiro
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: 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.
Propositions about Propositions 3
S.C. Shapiro
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Representing Propositions
• Representation of Proposition
– Not by a Logical Sentence
– But by a Functional Term
– Denoting a Proposition.
S.C. Shapiro
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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)
S.C. Shapiro
cse@buff
alo
Outline
• Introduction
• Intensional Entities
• Complex Categories
• Possession I
• Propositions about Propositions
• Possession II
• Summary
S.C. Shapiro
cse@buff
alo
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 representationwith later reasoning.
S.C. Shapiro
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alo
: 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.
Possession II.2
S.C. Shapiro
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: What is an inalienable possession?
I don't know.
: What is an alienable possession?
I don't know.
Possession II.3
S.C. Shapiro
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alo
: Hands are body parts.
I understand that hands are body parts.
: Books are ownable objects.
I understand that books are ownable objects.
Possession II.4
S.C. Shapiro
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: What is Stu's hand?
Stu’s hand is the hand.
: What is Bill's book?
Bill’s book is the book.
Possession II.5
S.C. Shapiro
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: 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.
Possession II.6
S.C. Shapiro
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PseudoRepresentation of Possession
• 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
cse@buff
alo
Outline
• Introduction
• Intensional Entities
• Complex Categories
• Possession I
• Propositions about Propositions
• Possession II
• Summary
S.C. Shapiro
cse@buff
alo
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
cse@buff
alo
SNePS Research GroupCurrent Members
• Faculty:Stuart C. Shapiro, DirectorWilliam J. Rapaport, Associate DirectorCarl AlphonceJean-Pierre A. KoenigDavid R. Pierce
• Graduate Students:Marc Broklawski Bharat BhushanDebra T. Burhans Haythem O. IsmailFrances L. Johnson John F. Santore