An Institution-independent Generalization of Tarski's Elementary Chain Theorem

Abstract

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. These include the unconditional equational, positive, ð� [ � Þ 0 and full first-order logics, as well as less conventional logics, used in computer science, such as hidden or rewriting logic.