Defining distances for all process semantics

Abstract

Recently several authors have proposed some notions of distance between processes that try to quantify “how far away” is a process to be related with some other with respect to a certain semantics. These proposals are usually based on the simulation game, and therefore are mainly defined for simulation semantics or other semantics more or less close to these. These distances have a local character since only one of the successors of each state is taken into account in their computation. Here, we present an alternative proposal exploiting the fact that processes are trees. We define the distance between two of them as the cost of the transformations that we need to apply to get two processes related by the corresponding semantics. Our new distances can be uniformly defined for all the semantics in the ltbt-spectrum.