In graph theory a process-graph or P-graph is a directed bipartite graph used in workflow modeling.
The vertices of the graph are of two types, operation (O) and material (M). The two vertex types form two disjunctive sets. The edges of the graph link the O and M vertices. An edge from an operation vertex (O) connects to a material vertex (M) if M is the output of O, such as a 'document' (material) that is output by a 'write-up' (operation). An edge from M to O indicates that M is an element of the input set of O, e.g. a document may be part of the input to a 'review' operation.
Applications
Process-graph is in use in different fields of application in Process Synthesis. An example for an application is Process Network Synthesis. The method is in scientific use to find optimum process chains in chemical formulas, energy technology networks and other optimisation problems like evacuation routes in buildings or transportation routes.