For reasons of technical convenience, current retrieval algorithms based on probabilistic reasoning are derived from models that assume patrons evaluate documents using a two value relevance scale. This paper extends the theory by describing a model which includes a more general relevance scale....

M. H. Heine has shown that if one follows the retrieval procedure associated with Swets' model of an information retrieval system it is possible that the inverse relationship between Recall and Precision may not hold. In this paper we extend Heine's result to the case where the...