Answer set programs with optional rules: a possibilistic approach
Kim Bauters, Steven Schockaert, Martine De Cock, Dirk Vermeir · Ghent University Academic Bibliography (Ghent University) · 2013
Many problems in artificial intelligence can be en-coded as answer set programs (ASP) in which some rules are uncertain. ASP programs with incorrect rules may have erroneous conclusions, but due to the non-monotonic nature of ASP, omitting a cor-rect rule may also lead to errors. To derive the most certain conclusions from an uncertain ASP program, we thus need to consider all situations in which some, none, or all of the least certain rules are omitted. This corresponds to treating some rules as optional and reasoning about which con-clusions remain valid regardless of the inclusion of these optional rules. While a version of possibilistic ASP (PASP) based on this view has recently been introduced, no implementation is currently avail-able. In this paper we propose a simulation of the main reasoning tasks in PASP using (disjunc-tive) ASP programs, allowing us to take advantage of state-of-the-art ASP solvers. Furthermore, we identify how several interesting AI problems can be naturally seen as special cases of the considered reasoning tasks, including cautious abductive rea-soning and conformant planning. As such, the pro-posed simulation enables us to solve instances of the latter problem types that are more general than what current solvers can handle. 1