Pre-indexed terms for Prolog

Indexing of terms and clauses is a well-known technique used in Prolog implementations (as well as automated theorem provers) to speed up search. In this paper we show how the same mechanism can be used to implement efficient reversible mappings between different term representations, which we call pre-indexings. Based on user-provided term descriptions, these mappings allow us to use more efficient data encodings internally, such as prefix trees. We show that for some classes of programs, we can drastically improve the efficiency by applying such mappings at selected program points