CSP for parallelising Brzozowski's DFA construction algorithm

CSP, a simple and elegant process algebra, is used to specify five successive parallel versions of Brzozowski’s sequential algorithm for constructing deterministic finite automata from regular expressions. Early versions were not sufficiently mature to easily map to a programming language. However, each version exposed new possibilities for refinement so that later versions could subsequently be implemented (in Go). The exercise illustrates the value of the lightweight use of process algebras for supporting abstract thinking when attempting to solve computational problems in a parallel fashion. The emphasis here is on algorithm specification and not on the implementation.