Soft Pattern Models

August 17, 2005

Generic Soft Pattern Models for Definitional QA

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Bigram Model in Dealing with Gaps

•Bigram model can deal with gaps

–Unseen tokens have small smoothing probabilities in specific positions

<Search_Term> which is known for DT$ NNP

Test sentence:

Pattern

<Search_Term> , whose book is known for

P(“,”|S1) = P(“whose”|S2) = P(“book”|S3) = P(“is”|S4) =

P(“,”|S1) = P(“whose”|S2) … = small smoothing prob

P(“known”|S3) = 0.3 P(“for”|S4) = 0.21

Not too good!