Two models of retrieval with probabilistic indexing

Abstract

We describe two retrieval models for probabilistic indexing. The binary independence indexing (BII) model is a generalized version of the Maron & Kuhns indexing model. In this model, the indexing weight of a descriptor in a document is an estimate of the probability of relevance of this document with respect to queries using this descriptor. The retrieval-with-probabilistic-indexing (RPI) model is suited to different kinds of probabilistic indexing. Therefore we assume that each indexing model has its own concept of 'correctness' to which the probabilities relate. The concept of correctness is not necessarily identical with the concept of relevance, it is only required to depend on relevance. In addition to the probabilistic indexing weights, the RPI model provides the possibility of relevance weighting of search terms. Both retrieval models are compared in experiments, showing equally good results.