Zbigniew Lonc

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Let G be the set of finite graphs whose vertices belong to some fixed countable set, and let ≡ be an equivalence relation on G. By the strengthening of ≡ we mean an equivalence relation ≡s such that The most important case that we study in this paper concerns equivalence relations defined by graph properties. We write G ≡ Φ H, where Φ is a graph property(More)
We propose and study algorithms to compute minimal models, stable models and answer sets of t-CNF theories, and normal and disjunctive t-programs. We are especially interested in algorithms with non-trivial worst-case performance bounds. The bulk of the paper is concerned with the classes of 2-and 3-CNF theories, and normal and disjunctive 2-and 3-programs,(More)
The well-founded semantics is one of the most widely studied and used semantics of logic programs with negation. In the case of finite propositional programs, it can be computed in polynomial time, more specifically, in O(|At(P)|×size(P)) steps, where size(P) denotes the total number of occurrences of atoms in a logic program P. This bound is achieved by an(More)