Active Tokens for Modelling Mental Health Care with Coloured Stochastic Petri Nets

Petri nets are a well-known paradigm for simulating dynamic systems. Coloured Petri nets are characterised by tokens with attributes whose values are changed by events in the model. They cannot play an active role in the system behaviour. Using them to model human beings, with continuously changing attributes and simple decision-making abilities, would require a large number of auxiliary elements in the net, resulting in a significant loss of clarity in the model. In this paper we would like to introduce the concept of active tokens in coloured stochastic Petri nets that enables the modelling of changing attributes independently of system events and without adding further elements to the net. The proposed concept extends the tokens by methods for event-independent attribute dynamics. We demonstrate the principle of active tokens by an example from mental health care.