1. A computer-implemented method of improving performance of a computer to enhance relevance ranking of results in a computer-implemented search of a corpus of documents having in part homogeneous structured data having a field structure, using an underlying search engine offering a distribution-biased OR operator, the method comprising: a. as a preparatory phase, before a request function receives any queries, based on knowledge of the field structure of the documents to be searched and the content of some of the fields, determining a mapping or policy for automatically, by a processor, replacing a received search clause with a sequence of multiple search clauses of anticipated nested respective responsive scopes, such that a set of documents responsive to one search clause in the sequence of search clauses is predicted to be a subset of the set of documents responsive to the next search clause in the sequence of search clauses; b. on an ongoing basis, operating at a search-controller level to mediate between the request function and an underlying search engine, and electronically receiving a query comprising at least one search clause from the request function; c. by the processor, according to the mapping or policy determined in preparatory-phase step (a), transforming at least one of the at least one received search clause received in step (b) into an automatically generated, intentionally redundant sequence of search clauses representing the anticipated nesting of respective responsive scopes designed in the step (a) mapping or policy, so as to correspond to gradations of focus on a topic of interest interpreted to be suggested by the at least one received search clause; d. combining the generated sequence of search clauses with a distribution-biased OR operator and submitting the combination to the underlying search engine to be executed against a database associated with the search engine, wherein scoring of the distribution-biased OR operation reflects not only aggregate scoring from respective counts of matches for the alternate clauses under the distribution-biased OR but also the evenness of distribution of that aggregate across its contributing component scores coming from those respective alternate clauses; e. automatically executing the submitted combination of search clauses, by the underlying search engine, such that the nesting of the individual clauses' respective responsive scopes induces scopes of focus induce the underlying search engine to return a set of responsive documents for the entire OR combination that corresponds to the responsive set for the broadest of the submitted, automatically generated sequence of individual search clauses; and f. automatically relevance-scoring the broad set of responsive documents returned in step (e), via the underlying search engine's processing of the distribution-biased OR-connected sequence of search clauses automatically generated and submitted in steps (c) and (d), yielding scoring more sensitive to gradations of focus on a topic of interest as suggested in the at least one search clause received in step (b).