We introduce a new method (derived from model theoretic general combination procedures in automated deduction) for proving fusion decidability in modal systems. We apply it to show fusion decidability in case not only the boolean connectives, but also a universal modality and nominals are shared symbols.

A new semantics with the finite model property is provided and used to establish decidability for Gödel modal logics based on (crisp or fuzzy) Kripke frames combined locally with Gödel logic. A similar methodology is also used to establish decidability, and indeed co-NPcompleteness for a Gödel S5 logic that coincides with the one-variable fragment of first-order Gödel logic.

We will discuss severai recentI) developed :e_h.ci;ues for prcving the decidability of the equivalence problem for devices den #III& languages and relations. Most of these techniques come from the development originat,d 1;1 the proof of the decidability of the DOL equivalence problem. Of particular importance is c.te recently shown validity of the Ehrenieucht conjecture and its effective variat...

In this paper we introduce a decidable fixpoint extension of temporal Description Logics. We exploit the decidability results obtained for various monodic extensions of Description Logics to obtain decidability and tight complexity results for temporal fixpoint extensions of these Description Logics and more generally for the decidable monodic fragments of first order logic.

We investigate the problem of deciding whether a system linear equations, together with divisibility conditions on variables, has solution over holomorphy subrings global fields. obtain decidability results when we allow poles at cofinite set places, and undecidability finite places.

We consider fragments of first-order logic and as models we allow finite and infinite words simultaneously. The only binary relations apart from equality are order comparison < and the successor predicate +1. We give characterizations of the fragments Σ2 = Σ2[<,+1] and FO2 = FO2[<,+1] in terms of algebraic and topological properties. To this end we introduce the factor topology over infinite wo...

We suggest a simple and clean deenition for Well-Structured Transition Systems Fin90,A CJY96], a general class of innnite state systems for which decidability results exist. As a consequence we can (1) generalize the deenition in many ways, (2) nd examples of (general) WSTS's in many elds, and (3) present new decidability results.

We give new, conceptually different, and hopefully more easily understandable proofs for two results on transducers: the decidability of k-valuedness (Gurari-Ibarra’s theorem) and the decidability of bounded valuedness (Weber’s theorem). Our constructions yield algorithms that closely depend on the structure of the transducers, and better complexity bounds.

We prove that a semigroup generated by a reversible two-state Mealy automaton is either finite or free of rank 2. This fact leads to the decidability of finiteness for groups generated by two-state or two-letter invertible-reversible Mealy automata and to the decidability of freeness for semigroups generated by two-letter invertible-reversible Mealy automata.

We prove decidability of satisfiability of sentences of the monodic packed fragment of firstorder temporal logic with equality and connectives Until and Since, in models with various flows of time and domains of arbitrary cardinality. We also prove decidability over models with finite domains, over flows of time including the real order.