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Web Information retrieval (Web IR)

Web Information retrieval (Web IR). Handout #8: Probabilistic information retrieval. Ali Mohammad Zareh Bidoki ECE Department, Yazd University alizareh@yaduni.ac.ir. Outline. R(q,d)= P(d,|q). Okapi BM25 Algorithm. f ( qi,D ) is the occurrences of qi in the document D

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Web Information retrieval (Web IR)

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  1. Web Information retrieval (Web IR) Handout #8:Probabilistic information retrieval Ali Mohammad Zareh Bidoki ECE Department, Yazd University alizareh@yaduni.ac.ir

  2. Outline • R(q,d)= P(d,|q)

  3. Okapi BM25 Algorithm • f(qi,D) is the occurrences of qi in the document D • f(qi;Q) is the occurrences of qi in the query Q • |D|is the length of the document D (i.e., the number of words), and avgdl is the average document length • k1, k3 and b are free • parameters. Usually set k1 = 2.5, k3 = 0 and b = 0.8.

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