We give an institution-independent definition of reachable model, and we apply it to obtain a new institution by enhancing the syntax of a base institution with constructors and restricting the semantics to reachable models.Expand

We express and prove the completeness of infinitary firstorder logics in the institution-independent setting by using forcing, a powerful method for constructing models.Expand

We prove an institutional version of Tarski's elementary chain theorem applicable to a whole plethora of ‘first-orderaccessible’ logics, which are, roughly speaking, logics whose sentences can be constructed from atomic formulae by means of classical first-order connectives and quantifiers.Expand

We develop an abstract proof calculus for hybrid logics whose sentences are (hybrid) Horn clauses, and we prove a Birkhoff completeness theorem in the general setting provided by the institution theory.Expand

The present paper describes a method for proving Downward Lowenheim-Skolem Theorem within an arbitrary institution satisfying certain logic properties.Expand

In the context of proliferation of many logical systems in the area of mathematical logic and computer science, we present a generalization of forcing in institution-independent model theory which is used to prove two abstract results: Downward Löwenheim-Skolem Theorem and Omitting Types Theorem.Expand

Abstract The present contribution advances an abstract notion of hybrid logic by supplementing the definition of institution with an additional structure to extract frames.Expand