Fundamenta Informaticae 85 (2008) 219–234 219 IOS Press Token History Petri Nets Kees van Hee, Alexander Serebrenik ∗ , Natalia Sidorova Department of Mathematics and Computer Science Eindhoven University of Technology P.O. Box 513, 5600 MB Eindhoven, The Netherlands k.m.v.hee, a.serebrenik, n.sidorova@tue.nl Abstract. State of the art information system commonly record events in log files, also known as audit trails. Moreover, business processes often go beyond the sole recording the events and base decisions on the events observed in the past. To model such processes we extend the basic Petri net framework with the notion of history by associating tokens with histories, adding guards evaluated on the history to the transitions and mapping arcs to expressions involving histories. Guards and arc expressions can involve data associated with the transitions. 1. Introduction Most industrial enterprise information systems keep track of all events taking place within the system as part of their basic functionality. Recording history of every case is also a standard practice for work- flow [2] and case-handling systems [11]. There this history is not only used for archiving but also for decision making, e.g. the credit history of a person is used negotiation a loan. We refer to this kind of systems as history-dependent systems. A natural way to model history-dependent systems is by incorporating case histories directly into the model. Since these systems are often distributed systems with multiple processes running in parallel and multiple decision points, Petri nets are a very suitable candidate for the basis of our model. To extend them with a history feature, we consider coloured Petri nets where tokens have history as their colour. Transition guards are evaluated on the union of the histories of the tokens consumed during the firing and the tokens produced by a firing have histories according to the arc expressions. ∗ Address for correspondence: Department of Mathematics and Computer Science, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands