BIM
IR as Classification (relevant or not) with
Bayes Decision Rule Assumes the relevance between documents and queries as binary variables (0 or 1)
P(D∣R)=∏i:di=1pi∏i:di=0(1−pi)
P(D∣NR)=∏i:di=1si∏i:di=0(1−si) Scoring function
S(D)=logP(D∣NR)P(D∣R) S(D)=∑i:di=1logsipi+∑i:di=0log1−si1−pi