Abstract

Applications of logic and in particular of model theoretic methods are often governed by specific semantic constraints that are best treated as game induced invariance conditions. Important examples include bisimulation invariance, pebble-game invariance and guarded bisimulation invariance. Within some domain that is characterised by a certain game invariance one can examine model theoretic questions (expressive completeness, satisfiability, descriptive complexity, recursion mechanisms) with tools intimately related to the underlying games. This talk provides a survey of correponding results with emphasis on the comparative study of the guarded, modal and two-variable domains, and on the methodological transfer between modal and guarded logics.