1. AQUAINT Workshop June 2002 Computational Implicatures for Advanced Question Answering Sanda Harabagiu University of Texas at Dallas

2. AQUAINT Workshop June 2002 - ImpliQA The Problem  A professional analyst cannot separate his/her intentions and beliefs from the formulation of a question.  Sometimes the analyst makes a proposal or assertion.  Implied information, important for the interpretation of a question.  Not recognizable at syntactic or semantic level.  Determines the quality of answers returned by the Q/A system.

3. AQUAINT Workshop June 2002 - ImpliQA Example “Will Prime Minister Mori survive the crisis?”  Implied belief: the position of Prime Minister is in jeopardy.  Problem: none of the question words indicate directly danger.  Question expected answer type: survival  Implicature: DANGER

4. AQUAINT Workshop June 2002 - ImpliQA

5. AQUAINT Workshop June 2002 - ImpliQA Recognizing the intention of a question  Analyst implication: Camdessus lead IMF, but was succeeded by someone else.  The intention of Q1 was understood.

6. AQUAINT Workshop June 2002 - ImpliQA Novelties of our Model of Question Implicatures 1)Derive all and only the inferences intended by the analyst. 2)Tractable procedures for question. interpretation and coercion of implicatures. 3)Cognitively plausible model of question implicatures. 4)Model diachronically how certain implicatures become semi-conventional.

7. AQUAINT Workshop June 2002 - ImpliQA Using Pragmatic Knowledge for Question Interpretation Will Prime Minister Mori survive the political crisis?  the analyst is not literary meaning “Will Prime Minister Mori be still alive when the political crisis is over?”  but expresses the belief that the current political crisis might cost the Japanese Prime Minister his job.

8. AQUAINT Workshop June 2002 - ImpliQA Question Interpretation through Topical Relations  Question: Will Prime Minister Mori survive the political crisis ?  concepts: prime minister, survive, political crisis  Problem 1: WordNet encodes political and crisis as two different concepts  Problem 2: semantic ambiguity  Problem 3: should we coerce all concepts topically related to each of the question concepts ?  Problem 4: How do we know that the question is literal or figurative ?

9. AQUAINT Workshop June 2002 - ImpliQA Ideal Derivation of Pragmatic Knowledge

10. AQUAINT Workshop June 2002 - ImpliQA Complete Coercion prime ministersurvivepolitical crisis PERSON (sense 1) in England PERSON (sense 2) in other countries JOB (sense 3) unstable situation crucial stage or turning point extreme danger Subject Select the name entity Verb Object Select the most specific concept: danger

11. AQUAINT Workshop June 2002 - ImpliQA Interpretation via Redundancy  Danger words: resignation, removal, strike, vote – all in political arena “Vote of non-confidence against Prime Minister Mori ”  Need for world knowledge: vote of non-confidence  Danger(vote) CAUSE: DANGER (Position) danger(Position)

12. AQUAINT Workshop June 2002 - ImpliQA Method of Generating Automatically Expansion Dictionaries in a Given Domain  1. Establish the domain: prime minister  politician political crisis  2. Use manually created domain taxonomies (e.g. yahoo.com) to collect seed examples of expanded words:  3. Use all WordNet synonyms of all senses of word DANGER: {danger, risk, peril} ISA politics governmentelections collect all the document documents

13. AQUAINT Workshop June 2002 - ImpliQA Empirical Methods 4.1. Generate word windows centered around each occurrence of a DANGER-word (WINDOW SIZE=200 words) 4.2. Order by frequency of the stem all content words from all windows 4.3 Select the 5 most frequent nouns 4.4 Let PFreq indicate their frequency in the Yahoo documents 4.5 Use each noun with any DANGER word to formulate a query for Google 4.6. Compute the frequency SFreq with which these words occurred as Subjects or OBJECTS in the documents returned by Google

14. AQUAINT Workshop June 2002 - ImpliQA Expand the Dictionary 1. Compute P = for each candidate word if (SFreq  3) or (SFreq  2) and (P  0.1) add the word to the dictionary 2. Establish a relation with the other concepts of the question. Example: DANGER(relation) = R 3. Compute a semantic density measure between the new danger word and the different senses of the question concept prime ministervote R question concept new DANGER word

15. AQUAINT Workshop June 2002 - ImpliQA Semantic Density Measured by the density of common words between the hierarchies of C q (the question concept) and C N (new word from dictionary) where cc is the number of common content words occurring in the glosses of the WordNet subhierarchies of C N and C q

16. AQUAINT Workshop June 2002 - ImpliQA Resolution of Relation Density (vote, {position, job}) > Density (vote, {person}) DANGER (vote) |– DANGER(position)

17. AQUAINT Workshop June 2002 - ImpliQA Question Interpretation “Will Prime Minister Mori survive the political crisis” Q’: Will Prime Minister Mori ‘s position be endangered by the political crisis ? Q’’: How will Prim Minister Mori’s position be affected by the political crisis? no more survive verb

18. AQUAINT Workshop June 2002 - ImpliQA Linguistic Phenomenon: Metonymy  Referential metonymies The ham sandwich is waiting for his check (Lakoff & Johnson) (Q1) Which wide-body jets serve dinner?  Predicative metonymies The car drinks gasoline (Wilks) (Q2) Which airlines fly from Boston to Denver? (ATIS domain)

19. AQUAINT Workshop June 2002 - ImpliQA Implications as metonymies How will George W. Bush revive the economy? In a bid to revive the US economy, President George W Bush has called for his sweeping tax cutting plans to take effect from the beginning of this year, saying 'I strongly believe that a tax relief plan is an important part of helping our country 's economy recover, and I think expediting money into people 's pockets is going to be a key ingredient... What feeds teenage violence? Anger at the system, that universal aspect of teenage rebellion, and probably the central driving force, building a macho cool reputation…

20. AQUAINT Workshop June 2002 - ImpliQA Knowledge Coercion

21. AQUAINT Workshop June 2002 - ImpliQA Metonymic functions  Container for contents  The kettle is boiling  Producer for product  He bought a Ford.  Object used for user  The buses are on strike.  Artist for art form  Ted is playing Bach.

22. AQUAINT Workshop June 2002 - ImpliQA Pragmatics of Q/A

23. AQUAINT Workshop June 2002 - ImpliQA Immediate plans  Methods for detecting figurative senses of questions sortal constraints selectional restrictions redundant patterns  Methods for coercing the implied knowledge epistemic logic Web as a KB – cotraining methods for rapid knowledge formation

24. AQUAINT Workshop June 2002 - ImpliQA Thank You !