**4.3. Computing synchronous distance**

All transition sequences can be found on the graph G(Σ). Synchronous distances, weighted or not, are defined in terms of transition sequences. Thus, it is possible to design algorithms for the computing of distances. Firstly, if a ring exists on G(Σ) that contains different numbers of firings of T1 transitions and T2 transitions, the distance is ∞. All algorithms are designed for computing finite distances only. The book in Chinese entitled *Petri Net Applications* by the author will soon appear, in which an algorithm for the computing of synchronous distances in P/T-systems can be found. It is easy to design an algorithm for computing weighted distances based on this algorithm.

We go no further on synchronous distances in this chapter since what concerns us is workflow modelling and what has been said about synchronous distances is already sufficient.
