Degrees of Laziness in Grounding: Effects of Lazy-Grounding Strategies on ASP Solving

TL;DR

This paper explores various degrees of lazy grounding in ASP, proposing new strategies, analyzing their formal properties, and demonstrating through experiments that some outperform existing methods in solving large-scale problems.

Contribution

It introduces a formal characterization of lazy grounding degrees, new strategies, and an empirical evaluation showing improved ASP solving performance.

Findings

Certain lazy grounding strategies outperform state-of-the-art methods

Formal relationships between grounding degrees are established

Experimental results demonstrate significant performance improvements

Abstract

The traditional ground-and-solve approach to Answer Set Programming (ASP) suffers from the grounding bottleneck, which makes large-scale problem instances unsolvable. Lazy grounding is an alternative approach that interleaves grounding with solving and thus uses space more efficiently. The limited view on the search space in lazy grounding poses unique challenges, however, and can have adverse effects on solving performance. In this paper we present a novel characterization of degrees of laziness in grounding for ASP, i.e. of compromises between lazily grounding as little as possible and the traditional full grounding upfront. We investigate how these degrees of laziness compare to each other formally as well as, by means of an experimental analysis using a number of benchmarks, in terms of their effects on solving performance. Our contributions are the introduction of a range of novel lazy grounding strategies, a formal account on their relationships and their correctness, and an investigation of their effects on solving performance. Experiments show that our approach performs significantly better than state-of-the-art lazy grounding in many cases.