lemur::retrieval::SimpleKLScoreFunc Class Reference

Simple KL-divergence scoring function. More...

#include <SimpleKLRetMethod.hpp>

Inheritance diagram for lemur::retrieval::SimpleKLScoreFunc:

List of all members.

Public Member Functions
void	setScoreMethod (enum SimpleKLParameter::adjustedScoreMethods adj)
virtual double	matchedTermWeight (const lemur::api::QueryTerm *qTerm, const lemur::api::TextQueryRep *qRep, const lemur::api::DocInfo *info, const lemur::api::DocumentRep *dRep) const
virtual double	adjustedScore (double origScore, const lemur::api::TextQueryRep *qRep, const lemur::api::DocumentRep *dRep) const
	score adjustment (e.g., appropriate length normalization)
Public Attributes
enum SimpleKLParameter::adjustedScoreMethods	adjScoreMethod

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Detailed Description

Simple KL-divergence scoring function.

The KL-divergence formula D(model_q || model_d), when used for ranking documents, can be computed efficiently by re-writing the formula as a sum over all matched terms in a query and a document. The details of such rewriting are described in the following two papers:

• C. Zhai and J. Lafferty. A study of smoothing methods for language models applied to ad hoc information retrieval, In 24th ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR'01), 2001.
• P. Ogilvie and J. Callan. Experiments using the Lemur toolkit. In Proceedings of the Tenth Text Retrieval Conference (TREC-10).

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Member Function Documentation

virtual double lemur::retrieval::SimpleKLScoreFunc::adjustedScore (  double  origScore, const lemur::api::TextQueryRep *  qRep, const lemur::api::DocumentRep *  dRep )  const [inline, virtual]

score adjustment (e.g., appropriate length normalization) The following are three different options for scoring ==== Option 1: query likelihood ============== ==== Option 2: cross-entropy (normalized query likelihood) ==== ==== Option 3: negative KL-divergence ====

virtual double lemur::retrieval::SimpleKLScoreFunc::matchedTermWeight (  const lemur::api::QueryTerm *  qTerm, const lemur::api::TextQueryRep *  qRep, const lemur::api::DocInfo *  info, const lemur::api::DocumentRep *  dRep )  const [inline, virtual]

void lemur::retrieval::SimpleKLScoreFunc::setScoreMethod (  enum SimpleKLParameter::adjustedScoreMethods  adj  )  [inline]

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Member Data Documentation

enum SimpleKLParameter::adjustedScoreMethods lemur::retrieval::SimpleKLScoreFunc::adjScoreMethod

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The documentation for this class was generated from the following file:

• SimpleKLRetMethod.hpp

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