Abstract

We represent state machines in the category of specifications, where assignment statements correspond exactly to interpretations be- tween theories [7, 8]. However, the guards on an assignment require a special construction. In this paper we raise guards to the same level as assignments by treating each as a distinct category over a shared set of objects. A guarded assignment is represented as a pair of arrows, a guard at'row and an assignment arrow. We give a general construction for combining at'rows over a factorization system, and show its specialization to the category of specifications. This construction allows us to define the fine structure of state machine morphisms with respect to guards.

Citations