1 research outputs found
Strong Equivalence for Epistemic Logic Programs Made Easy (Extended Version)
Epistemic Logic Programs (ELPs), that is, Answer Set Programming (ASP)
extended with epistemic operators, have received renewed interest in recent
years, which led to a flurry of new research, as well as efficient solvers. An
important question is under which conditions a sub-program can be replaced by
another one without changing the meaning, in any context. This problem is known
as strong equivalence, and is well-studied for ASP. For ELPs, this question has
been approached by embedding them into epistemic extensions of equilibrium
logics. In this paper, we consider a simpler, more direct characterization that
is directly applicable to the language used in state-of-the-art ELP solvers.
This also allows us to give tight complexity bounds, showing that strong
equivalence for ELPs remains coNP-complete, as for ASP. We further use our
results to provide syntactic characterizations for tautological rules and rule
subsumption for ELPs.Comment: Long version of paper published at AAAI'19, extended with full proof