Identification of DES Unobservable Behaviour by Petri Nets

The paper addresses the problem of the on-line identification of Petri Nets (PN) modelling the unobservable behaviour of Discrete Event Systems (DES). Starting from a previous specification of an identifier that monitors the DES events and the corresponding available place markings, the paper proves some results that make the on-line identification of reasonable complexity. Assuming that the PN system modelling the observable events is known, at each event occurrence an identification algorithm recursively updates and provides as an output the complete PN system describing both the observable and unobservable DES behaviour. An example shows an application of the proposed technique.