What happens in a workflow when a place contains more than one token?
In the Workflow system if a transition has a single input place then that place cannot hold more than one token as each time one lands on it the related transition is fired automatically and the token is instantly consumed. In this situation it is therefore impossible for a place to hold more than one token. If, however, a transition has multiple input places then it is possible for one of those places to hold more than one token at a time, as explained in the following example: • A transition ‘T’ has two input places, ‘P1’ and ‘P2’. • A token arrives on ‘P1’, but transition ‘T’ cannot fire because there is no token on ‘P2’. • A second token arrives on ‘P1’, but again transition ‘T’ cannot fire because there is no token on ‘P2’. • A token arrives on ‘P2’, so transition ‘T’ fires and consumes one token from both ‘P1’ and ‘P2’. This leaves one token on ‘P1’. The remaining token on ‘P1’ just sits there, waiting for a token to be placed on ‘P2’ so that its transition can be fired and it ca
