Non-Termination Inference of Logic Programs

TL;DR

This paper introduces a static analysis method for inferring non-termination in logic programs, extending subsumption tests and identifying specific argument positions to improve understanding of program behavior.

Contribution

It presents a novel static analysis framework that extends subsumption tests and automates non-termination inference for logic programs.

Findings

The approach effectively identifies non-terminating logic queries.

Experimental results show the method's accuracy and complementarity with termination analysis.

Algorithms automate the non-termination inference process.

Abstract

We present a static analysis technique for non-termination inference of logic programs. Our framework relies on an extension of the subsumption test, where some specific argument positions can be instantiated while others are generalized. We give syntactic criteria to statically identify such argument positions from the text of a program. Atomic left looping queries are generated bottom-up from selected subsets of the binary unfoldings of the program of interest. We propose a set of correct algorithms for automating the approach. Then, non-termination inference is tailored to attempt proofs of optimality of left termination conditions computed by a termination inference tool. An experimental evaluation is reported. When termination and non-termination analysis produce complementary results for a logic procedure, then with respect to the leftmost selection rule and the language used to describe sets of atomic queries, each analysis is optimal and together, they induce a characterization of the operational behavior of the logic procedure.