## 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].

### MSC:

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