We consider extensions of the two-variable guarded fragment, GF2, where distinguished
binary predicates that occur only in guards are required to be interpreted in a special way …

We show that modal logic over universally first-order definable classes of transitive frames is
decidable. More precisely, let K be an arbitrary class of transitive Kripke frames definable by …

Over the past two decades several fragments of first-order logic have been identified and
shown to have good computational and algorithmic properties, to a great extent as a result of …

We study variants of the satisfiability problem of elementary modal logics, ie, modal logic
considered over first-order definable classes of frames. The standard semantics of modal …

Modal logic was first introduced by philosophers to study the deductive behaviour of the
expressions it is necessary that and it is possible that. Nowadays, it is widely used in several …