Two possibly alternative approaches to the semantics of stochastic process calculi

In a recent paper, published in ACM Computing Surveys, we introduced a unifying framework to describe the semantics of process algebras, including their variants useful for modeling quantitative aspects of behaviors. In parallel with our work Luca Cardelli and Radu Mardare advocated a new approach to the se- mantics of stochastic process algebras based on measure theory. In this note, we briefly introduce the two approaches and contrast them by using both of them to describe the semantics of PEPA, one of the most known and used stochastic process algebra.