Answer set programs with queries over subprograms. (English) Zbl 1491.68046

Balduccini, Marcello (ed.) et al., Logic programming and nonmonotonic reasoning. 14th international conference, LPNMR 2017, Espoo, Finland, July 3–6, 2017. Proceedings. Cham: Springer. Lect. Notes Comput. Sci. 10377, 160-175 (2017).
Summary: Answer-set programming (ASP) is a declarative programming paradigm. In this paper we discuss two related restrictions and present a novel modeling technique to overcome them: (1) Meta-reasoning about the collection of answer sets of a program is in general only possible by external postprocessing, but not within the program. This prohibits the direct continuation of reasoning based on the answer to the query over a (sub)program’s answer sets. (2) The saturation programming technique exploits the minimality criterion for answer sets of a disjunctive ASP program to solve co-\(\mathsf {NP}\)-hard problems, which typically involve checking if a property holds for all objects in a certain domain. However, the technique is advanced and not easily applicable by average ASP users; moreover, the use of default-negation within saturation encodings is limited.
In this paper, we present an approach which allows for brave and cautious query answering over normal subprograms within a disjunctive program in order to address restriction (1). The query answer is represented by a dedicated atom within each answer set of the overall program, which paves the way also for a more intuitive alternative to saturation encodings and allows also using default-negation within such encodings, which addresses restriction (2).
For the entire collection see [Zbl 1367.68005].


68N17 Logic programming
68T27 Logic in artificial intelligence
68T30 Knowledge representation
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