RedAlert: Determinacy inference for Prolog

Abstract

This paper revisits the problem of determinacy inference addressing the problem of how to uniformly handle cut. To this end a new semantics is introduced for cut, which is abstracted to systematically derive a backward analysis that derives conditions sufficient for a goal to succeed at most once. The method is conceptionally simpler and easier to implement than existing techniques, whilst improving the latter's handling of cut. Formal arguments substantiate correctness and experimental work, and a tool called 'RedAlert' demonstrates the method's generality and applicability.

Mutual Exclusion by Interpolation

“…In our previous implementation of a determinacy inference [2], the time required to infer the mutual exclusion conditions dominated all other aspects of the analysis. We thus compare how the new approach compares against the time required for argument size analysed based on polyhedra [22].…”

“…A form of determinacy inference for Prolog with cut has recently been presented [2] that applies backward analysis [17] to reduce the problem to the task of finding groundness conditions on a set of variables under which two systems of constraints are mutually exclusive, that is, not simultaneously satisfiable. However, the derivation of these conditions proved to be by far the most time consuming component of the whole implementation [2].…”

“…These conditions have clear applications in logic programming [1,2] and possible applications in functional programming, as is explained in Section 2. The problem is how to compute these conditions simply and do so in a way that is efficient.…”

“…However, even whithin the simpler domain of linear constraints, it was not obvious how these conditions can be found except by repeated application of existential quantifier elimination [1,2], an operation that is fundamentally exponential [5]. In this paper we address this problem by providing an alternative and elegant way for computing mutual exclusion conditions over linear constraints by applying Craig interpolation [6], a topic that has attracted much interest recently in program verification [7].…”

Symbolic Evaluation Graphs and Term Rewriting — A General Methodology for Analyzing Logic Programs

“…18). Several approaches for determinacy analysis have been developed (e.g., [24,25,26,27,28,33]). Moreover, determinacy analysis is also needed for complexity analysis to detect nondeterministic Split nodes in Thm.…”