Interning Ground Terms in XSB

TL;DR

This paper details the implementation of interning ground terms in the XSB Tabled Prolog system, exploring its design, challenges, and performance benefits, and comparing it to previous approaches like Zhou and Have.

Contribution

It introduces a novel implementation of ground term interning in XSB, tailored for tabling Prolog systems, with performance analysis and simplification over prior methods.

Findings

Interning ground terms improves performance in XSB.

Implementation is simpler and tuned for XSB's representations.

Performance benchmarks show benefits of the approach.

Abstract

This paper presents an implementation of interning of ground terms in the XSB Tabled Prolog system. This is related to the idea of hash-consing. I describe the concept of interning atoms and discuss the issues around interning ground structured terms, motivating why tabling Prolog systems may change the cost-benefit tradeoffs from those of traditional Prolog systems. I describe the details of the implementation of interning ground terms in the XSB Tabled Prolog System and show some of its performance properties. This implementation achieves the effects of that of Zhou and Have but is tuned for XSB's representations and is arguably simpler.