Action Language BC+

TL;DR

BC+ is a new action language that bridges the gap between traditional action languages and modern Answer Set Programming, enabling more expressive modeling of actions and effects with existing ASP solvers.

Contribution

The paper introduces BC+, an action language that integrates modern ASP constructs, enhancing expressiveness and computational applicability compared to previous languages.

Findings

BC+ encompasses features of multiple existing action languages.

BC+ semantics are based on stable model semantics for propositional formulas.

An implementation extends cplus2asp to support BC+.

Abstract

Action languages are formal models of parts of natural language that are designed to describe effects of actions. Many of these languages can be viewed as high level notations of answer set programs structured to represent transition systems. However, the form of answer set programs considered in the earlier work is quite limited in comparison with the modern Answer Set Programming (ASP) language, which allows several useful constructs for knowledge representation, such as choice rules, aggregates, and abstract constraint atoms. We propose a new action language called BC+, which closes the gap between action languages and the modern ASP language. The main idea is to define the semantics of BC+ in terms of general stable model semantics for propositional formulas, under which many modern ASP language constructs can be identified with shorthands for propositional formulas. Language BC+ turns out to be sufficiently expressive to encompass the best features of other action languages, such as languages B, C, C+, and BC. Computational methods available in ASP solvers are readily applicable to compute BC+, which led to an implementation of the language by extending system cplus2asp.