Abstract
In a reactive Kripke model, evaluation of logical operators can cause reconfiguration of the model in which the formula is evaluated. Therefore, in reactive Kripke frames, the evaluation of a logical formula in a world depends both on the world in which the evaluation is made and on the worlds it has passed through previously. The result is an extended semantics, which can specify a class of modal logics more comprehensive than the class specified by ordinary Kripke frames. This paper introduces a metamodel for reactive Kripke frames, based on the concept of categorical sketch. We believe that the categorical sketch is an appropriate metamodel for specifying a Kripke frame model.