Business Process Behavior Is (almost) Free-choice

Pablo A. Straub and Carlos Hurtado L. [email protected] [email protected] Depto. de Ciencia de la Computaci on Universidad Cat olica de Chile Vicu~ na Mackenna 4860 (143) Santiago 22, Chile Abstract Petri-nets have been used to model and analyze business process behavior, both in pure form and as the semantics of visual formalisms. We and others have advocated the use of a restricted class of nets called free-choice nets. Restricting models to free-choice nets leads to a polynomial algorithm to decide a criterion for behavioral correctness that we call simple control, and to a theory of threads of control that explains behavioral anomalies. This paper shows that constructs used in most business process languages lead to free-choice nets, but there are behaviors that cannot be modeled using these constructs, like the cancellation of an activity. To model these behaviors, we introduce a novel behavioral construct called unbalanced connector, whose semantics is not freechoice.