Towards approximate equivalences of workflow processes

Abstract

Abstract Well-known notions of equivalence suchas trace equivalence and bisimulationhave been used to compare workflowprocesses; they describe the equiva-lence of processes whose activities areidentical in each step. Possessing ex-actly the same activity in each step isquite rigorous, and sometimes we maymeet processes which fail to fit thiscondition but which have quite simi-lar behavior. To characterize this kindof looser equivalences, we introduce anapproximate version of trace equiva-lence and bisimulation in this paper. Keywords : Workflow process, traceequivalence, bisimulation, approximateequivalence 1. Introduction Workflows (also known as workflowprocesses or business processes) are ac-tivities involving the coordinated exe-cution of single activities (task or work-task) performed by different processingentities. In the last two decades, work-flow system ability of providing an au-tomated support to the management ofbusiness processes has increasingly be-come well recognized as a competitivefactor for a company [1]. With rapidincreases in application domains thatuse workflow management systems, alarge number of workflowmodeling lan-guages such as Petri nets, process al-gebra, BPEL, and YAWL have beendeveloped. Even in a given modelinglanguage, it is often possible to de-fine multiple models of the same work-flow. Given the co-existence of differ-ent modeling languages and differentmodels of a workflow, there is a needfor some formal techniques that can beused to compare these process models.In the literature, some well-knownnotions of equivalence such as traceequivalence [2], strong and weak bisim-ulations [3, 4], and branching bisimu-lation [3, 5] have been used to com-pare workflow processes. These equiv-alences aim to answer when two work-flows are the same with respect to somecriterion; for example, two workflowsmay be identical under trace equiva-lence but are different when consider-ing strongernotions of equivalence suchas bisimulation. It is worth noting thatmost equivalence notions provide a bi-nary answer (i.e., two workflows areequivalent or not). It has been ar-gued by Alves de Medeiros et al. [6]