In: Hans-Jörg Kreowski, Ugo Montanari, Fernando Orejas et al. (Eds.): Lecture Notes in Computer Science, Vol. 3393: Formal Methods in Software and Systems Modeling: Essays Dedicated to Hartmut Ehrig on the Occasion of His 60th Birthday, pages 370-384. Springer-Verlag, 2005.
Abstract: In this paper, we propose a new,loose semantics for place/tran- sition nets based on transition systems and generalizing the reachability graph semantics. The loose semantics of a place/transition net reflects all its possible refinements and is given as a category of transition systems with alternative sequences of events over the net. The main result states that each plain morphism between two place/transitions nets induces a free construction between the corresponding semantic categories.