An interaction calculus for concurrent systems

In this work we describe a simple calculus (called interaction calculus) for the representation of concurrent systems. In this a system is collection of expressions (processes) that share a working space; their computational behaviour is determined by the interaction of processes. The calculus is an attempt to describe concurrent systems by means of a ``non functional'' calculus which is, in some sense, strictly related with the lambda-calculus: computations are carried out by substitutions, but in our calculus they are originated by a symmetric interaction between two expressions, instead of the functional application of an operator to its operand. In this way we lose some good features of lambda calculus (the confluence property for instance), but we gain the capability of representing concurrency and mobility; all the same, we will discover that functions can be nicely encoded in the calculus