Lecture 19: Question Answering

Kai-Wei ChangCS @ University of Virginia

kw@kwchang.net

Couse webpage: http://kwchang.net/teaching/NLP16

1CS6501-NLP

Question answering

CS6501– Natural Language Processing 2credit:ifunny.com

'Watson' computer wins at 'Jeopardy'

Question answering

vGo beyond search

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Go beyond traditional web search

Answer queries using structured knowledge

vGoogle Knowledge GraphvFacebook Graph SearchvBing’s Satori

Need to understand the query!

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Thefollowing slidesaremodified fromChristopherManning&Pandu Nayak’s intro.toIR.

ExamplefromFernandoPereira(GOOG)

Paradigms for question answering

vText-based approachesvTREC QA, IBM Watson

vStructured knowledge-based approachesvApple Siri, Wolfram Alpha, Facebook Graph

Search

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Task – Answer Sentence Selection

v Given a factoid question, find the sentence that v Contains the answerv Can sufficiently support the answer

Q: Who won the best actor Oscar in 1973?S1: Jack Lemmon was awarded the Best Actor Oscar for Save

the Tiger (1973).S2: Academy award winner Kevin Spacey said that Jack

Lemmon is remembered as always making time for others.

Scott Wen-tau Yih (ACL 2013) paper

Lemmon was awarded the Best Supporting Actor Oscar in 1956 for Mister Roberts (1955) and the Best Actor Oscar for Save the Tiger (1973), becoming the first actor to achieve this rare double…Source: Jack Lemmon -- Wikipedia

Who won the best actor Oscar in 1973?

AssumethatthereisanunderlyingalignmentDescribeswhichwordsinandcanbeassociated

What is the fastest car in the world?

The Jaguar XJ220 is the dearest, fastest and most sought after car on the planet.

Word Alignment for Question AnsweringTREC QA (1999-2005)

See if the (syntactic/semantic) relations support the answer

[Harabagiu & Moldovan, 2001]

Knowledge-based QA

vBuild a semantic representation of the queryvTimes, dates, locations, entities, numeric quantities

vMap from this semantics to query structured data or resourcesvDatabase vOntologies (Wikipedia infoboxes, dbPedia,

WordNet, Yago)vScientific databases

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Linking Open Data cloud Diagram

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http://lod-cloud.net/