  In the task of information retrieval the term relevance is taken to mean
formal conformity of a document given by the retrieval system to user's
information query. As a rule, the documents found by the retrieval system
should be submitted to the user in a certain order. Therefore, a retrieval
perceived as a selection of documents formally solving the user's query, should
be supplemented with a certain procedure of processing a relevant set. It would
be natural to introduce a quantitative measure of document conformity to query,
i.e. the relevance measure. Since no single rule exists for the determination
of the relevance measure, we shall consider two of them which are the simplest
in our opinion. The proposed approach does not suppose any restrictions and can
be applied to other relevance measures.
