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Knowledge Representation for Natural Language Competence

This paper discusses the use of knowledge representation and reasoning systems for deep understanding of natural language texts. It explores issues in representing intensional entities, complex categories, and possession in order to achieve effective natural language competence.

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Knowledge Representation for Natural Language Competence

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  1. 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

  2. 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

  3. 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

  4. Interaction with Cassie (Current) Set of Beliefs [SNePS] English (Statement, Question, Command) Reasoning Clarification Dialogue Looking in World GATN Parser (Updated) Set of Beliefs [SNePS] (New Belief) [SNePS] Answer [SNIP] Actions [SNeRE] GATN Generator Reasoning English sentence expressing new belief answering question reporting actions S.C. Shapiro

  5. Outline • Introduction • Intensional Entities • Complex Categories • Possession I • Propositions about Propositions • Possession II • Summary S.C. Shapiro

  6. 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

  7. 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

  8. Intensional Entities 3 : LoisLanesawClarkKent. I understand that Lois Lane saw Clark Kent. : DidLois 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

  9. 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

  10. 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

  11. Intensional Entities 6 The evening star The morning star Venus Go to Go to ClarkKent Superman Buck Rogers See Lois Lane S.C. Shapiro

  12. Outline • Introduction • Intensional Entities • Complex Categories • Possession I • Propositions about Propositions • Possession II • Summary S.C. Shapiro

  13. 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

  14. 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

  15. 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

  16. 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

  17. PseudoRepresentation of Complex Categories • Isa(B30, CompCat(orange, CompCat(juice, seat))) • Isa(Pat, CompCat(excellent, teacher)) • Isa(Lucy, CompCat(former, teacher)) S.C. Shapiro

  18. Outline • Introduction • Intensional Entities • Complex Categories • Possession I • Propositions about Propositions • Possession II • Summary S.C. Shapiro

  19. Possession I.1 • “One man’s meat is another man’s poison.” S.C. Shapiro

  20. 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

  21. 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

  22. PseudoRepresentation of Possession • Has(Richard, meat, B35) • Has(Henry, poison, B37) • Equiv(B35, B37) S.C. Shapiro

  23. Outline • Introduction • Intensional Entities • Complex Categories • Possession I • Propositions about Propositions • Possession II • Summary S.C. Shapiro

  24. 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

  25. 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. S.C. Shapiro

  26. 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

  27. Representing Propositions • Representation of Proposition • Not by a Logical Sentence • But by a Functional Term • Denoting a Proposition. S.C. Shapiro

  28. 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

  29. Outline • Introduction • Intensional Entities • Complex Categories • Possession I • Propositions about Propositions • Possession II • Summary S.C. Shapiro

  30. 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

  31. 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

  32. Possession II.3 : What is an inalienable possession? I don't know. : What is an alienable possession? I don't know. S.C. Shapiro

  33. 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. S.C. Shapiro

  34. 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

  35. 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

  36. 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

  37. Outline • Introduction • Intensional Entities • Complex Categories • Possession I • Propositions about Propositions • Possession II • Summary S.C. Shapiro

  38. 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

  39. SNePS Research GroupCurrent Members • Faculty: Stuart C. Shapiro, Director William J. Rapaport, Associate Director Carl Alphonce Jean-Pierre A. Koenig David R. Pierce • Graduate Students: Marc Broklawski Bharat Bhushan Debra T. Burhans Haythem O. Ismail Frances L. Johnson John F. Santore S.C. Shapiro

  40. For More Information • URL:http://www.cse.buffalo.edu/~shapiro/ • Group:http://www.cse.buffalo.edu/sneps/ S.C. Shapiro

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