HISTORICAL REMARKS

Process algebra, as described in this book, has for the most part been the work of people at the Centre of Mathematics and Computer Science in Amsterdam. There, J.A. Bergstra and J.W. Klop started with the theory PA in 1982, motivated by a question of J.W. de Bakker (see [BERGSTRA & KLOP [1982]). As a general reference to their work, see BERGSTRA & KLOP [1984b], in which a fairly detailed discussion of related work can be found as well. The most extensive treatment of their work can be found in the Dutch book BAETEN [1986], which was the starting point for this book.

Compared to other concurrency theories, this work is closely related to the work on CCS. The theory of CCS is briefly discussed in the following section 8.2. The seminal work of MlLNER [1980] in which CCS was introduced, clearly sets out the goals of algebraic concurrency theory. We may see the theory of ACPτ as a remodularization of CCS. CCS has been worked out and extended in the work of HENNESSY & PLOTKIN [1980] and HENNESSY [1983]. See also HENNESSY & MlLNER [1985], GRAF & SIFAKIS [1984] and BROOKES & ROUNDS [1981]. MILNE [1982] has the so-called ‘dot calculus’, with · as parallel composition, prefix multiplication, two operators for alternative composition (internal and external choice) and, in contrast with Milner, n-ary communication.