Counting the cost in the picalculus.

Abstract

We design a new variation on the picalculus, ?cost, in which the use of channels or resources must be paid for. Processes operate relative to a cost environment, and communications can only happen if principals have provided sufficient funds for the channels associated with the communications. We define a bisimulation-based behavioural preorder in which two processes are related if, intuitively, they exhibit the same behaviour but one may be more efficient than the other. We justify our choice of preorder by proving that it is characterised by three intuitive properties which behavioural preorders should satisfy in a framework in which the use of resources must be funded.