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Natural Language Processing for the Web

Natural Language Processing for the Web. Prof. Kathleen McKeown 722 CEPSR, 939-7118 Office Hours: Wed, 1-2; Tues 4-5 TA: Yves Petinot 719 CEPSR, 939-7116 Office Hours: Thurs 12-1, 8-9. Today.

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Natural Language Processing for the Web

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  1. Natural Language Processing for the Web Prof. Kathleen McKeown 722 CEPSR, 939-7118 Office Hours: Wed, 1-2; Tues 4-5 TA: Yves Petinot 719 CEPSR, 939-7116 Office Hours: Thurs 12-1, 8-9

  2. Today • Next week: Invited Speaker SandaHarabagiu, Need 2 Discussants, location 414 CEPSR. This is not a class to miss! • Open Domain Question Answering (Lauren) • Natural language based reformulation resource and web exploitation for question answering (Kathy) • Improving QA Accuracy by Question Inversion (Vikas) • A Classification Approach to QA in Discussion Boards (Kenny) • Discussants: William, Shrenik

  3. When QA is difficult • When the answer string does not use the same words as the question string: • Who discovered America? • Columbus discovered America • Columbus Day celebrates the Italian Navigator who first landed in the New World on Oct. 12, 1942.

  4. Proposed Solution • Paraphrase Templates • How did Mahatma Gandhi die? • Mahatma Gandhi died <how> • Mahatma Gandhi died of <what> • Mahatma Gandhi died from <what> • Mahatma Gandhi’s death from <what> • Mahatma Gandhi drowned • Mahatma Gandhi suffocated • Mahatma Gandhi froze to death • <who> killed Mahatma Gandhi • <who> assassinated Mahatma Gandhi • Mahatma Gandhi was killed

  5. Use • In IR to find documents more likely to contain answer • To rank sentences within documents that are returned by IR

  6. Reformulations • Hand-built or manual generalizations of automatically produced paraphrases • Specify type of relation to original • Number of reformulations: 1-30, ave: 3.24

  7. Other Reformulation Types • Lexical: • Buy/sell: John sold the laptop to Mary = Mary bought the laptop from John • Syntactic: • How deep is Crater Lake? • Crater Lake has a depth of <what distance> • Inference • Reformulation Chains • Where did Bill Gates go to college? • Bill Gates was a student at <which college>? • Bill Gates dropped out of <which college>? • Bill Gates was a <which college> dropout? • Text: Bill Gates was a Harvard dropout.

  8. But…. Their Web IR System • Preserve quoted terms and quote the smallest NPs: • “What is the longest river in the United States?” -> “longest river” and “United States” • Expand the query using Wordnet Synonyms • “What is the length of the border between Ukraine and Russia?” -> (“length” or “distance”) and (“border” or “surround”) and (“Ukraine” or “Ukrainia”) and (“Russia” or “Soviet Union”) and (“between” or “betwixt”) • Using Contexrefomulations, add quoted reformulations of the question’s declarative form • “What is an atom?” -> “is an atom”, “an atom is” “an atom is one of”

  9. Evaluation

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