An algebra for data flow diagram process decomposition

Data flow diagram process decomposition, as applied in the analysis phase of software engineering, is a top-down method that takes a process, and its input and output data flows, and logically implements the process as a network of smaller processes. The decomposition is generally performed in an ad hoc manner by an analyst applying heuristics, expertise, and knowledge to the problem. An algebra that formalizes process decomposition is presented using the De Marco representation scheme. In this algebra, the analyst relates the disjoint input and output sets of a single process by specifying the elements of an input/output connectivity matrix. A directed acyclic graph is constructed from the matrix and is the decomposition of the process. The graph basis, grammar matrix, and graph interpretations, and the operators of the algebra are discussed. A decomposition procedure for applying the algebra, prototype, and production tools and outlook are also discussed