Similarity of generalized resources in Petri nets

Generalized resources are defined as multisets of Petri net vertices. Here places represent material resources (designated by tokens residing in these places). Transitions correspond to activity resources represented by transition firings. Two generalized resources are called similar if in any Petri net marking one resource can be replaced by another without changing the observable system's behaviour (modulo bisimulation). In this paper we study some basic properties of generalized resource similarity and prove that, being undecidable, generalized resource similarity is finitely based, and thus can be finitely described. We show also, that similarity of generalized resources allows to express some substantial properties of systems modelled by Petri nets.