A note on modal logic and possibility theory

There are two theories in which the concept of possibility plays an important role-modal logic and possibility theory. The roles are different, and so are the agendas of modal logic and possibility theory. To gain an insight into the differences, a very simple model of modal logic is constructed. The model has the structure of a finite-state system, referred to as the FS-model. The FS-model may be viewed as a simple interpretation of Kripke model-an interpretation which is easy to understand. The FS-model is in the spirit of graph models of modal logic. The FS-model readily lends itself to generalization. Concrete versions of the FS-model serve as examples.