Modulated Call/Return Evaluation strategies for Logic Programs

Abstract

Using the Logic Push-Down automata [LPDA] formalism to express resolution strategies, we show how new resolution strategies can be derived from a basic Call/Return-oriented strategy by (a) modulating the information flow and (b) applying some standard simplifications. The correctness of the resulting strategies is proved. This study takes place in the context of a tabular-based evaluation of the strategies (automatically given by the LPDA) where to focus on relevant information may avoid useless computations and reduce the cost of the tabulation. Keywords: Tabulation LPDA Resolution-Strategy Some proofs are provided in appendix in case the rewievers wish to check them. They are not part of the paper and may be ignored. 1 Introduction Tabulation-based logic program evaluators have renewed the interest in the spectrum of resolution strategies, outside the well known SLD and BottomUp strategies. Indeed, we can imagine all kinds of "mixed" strategies where OLD-like prediction is used to ..