FLINGO -- Instilling ASP Expressiveness into Linear Integer Constraints
This addresses a limitation for users of hybrid constraint answer set programming who need richer numerical expressiveness, though it is incremental as it builds on existing semantic foundations.
The paper tackles the loss of ASP expressiveness when numerical attributes are represented as constraints in CASP, by introducing FLINGO to incorporate features like default values and non-deterministic assignments into constraints, and provides a translation to standard CASP formats.
Constraint Answer Set Programming (CASP) is a hybrid paradigm that enriches Answer Set Programming (ASP) with numerical constraint processing, something required in many real-world applications. The usual specification of constraints in most CASP solvers is closer to the numerical back-end expressiveness and semantics, rather than to standard specification in ASP. In the latter, numerical attributes are represented with predicates and this allows declaring default values, leaving the attribute undefined, making non-deterministic assignments with choice rules or using aggregated values. In CASP, most (if not all) of these features are lost once we switch to a constraint-based representation of those same attributes. In this paper, we present the FLINGO language (and tool) that incorporates the aforementioned expressiveness inside the numerical constraints and we illustrate its use with several examples. Based on previous work that established its semantic foundations, we also present a translation from the newly introduced FLINGO syntax to regular CASP programs following the CLINGCON input format.