Abstract

this paper we consider how to express specications of interactions in dependent type theory. The results so far are modest, though we hope we have identied some key structures for describing contracts between independent agents, and shown how to dene them in a dependently typed framework. These are called below transition systems (2.2) and interaction systems (2.3). Both are coalgebras; transition systems for a functor Fam , and interaction systems for its composite with itself, Fam (Fam ). These structures seems to have interesting connections with predicate transformer semantics for imperative programs, as initiated by Dijkstra, and also with the renement calculus of Back and von Wright as described in their book [2]. We restrict attention to situations in which the system and its environment communicate by exchanging messages in strict alternation, as with the moves in a two player game.

Citations