  In this paper we present product-form solutions from the point of view of
stochastic process algebra. In previous work we have shown how to derive
product-form solutions for a formalism called Labelled Markov Automata (LMA).
LMA are very useful as their relation with the Continuous Time Markov Chains is
very direct. The disadvantage of using LMA is that the proofs of properties are
cumbersome. In fact, in LMA it is not possible to use the inductive structure
of the language in a proof. In this paper we consider a simple stochastic
process algebra that has the great advantage of simplifying the proofs. This
simple language has been inspired by PEPA, however, detailed analysis of the
semantics of cooperation will show the differences between the two formalisms.
It will also be shown that the semantics of the cooperation in process algebra
influences the correctness of the derivation of the product-form solutions.
