  For one-safe Petri nets or condition/event-systems, a process as defined by
Carl Adam Petri provides a notion of a run of a system where causal
dependencies are reflected in terms of a partial order. Goltz and Reisig have
generalised this concept for nets where places carry multiple tokens, by
distinguishing tokens according to their causal history. However, this
so-called individual token interpretation is often considered too detailed.
Here we identify a subclass of Petri nets, called structural conflict nets,
where no interplay between conflict and concurrency due to token multiplicity
occurs. For this subclass, we define abstract processes as equivalence classes
of Goltz-Reisig processes. We justify this approach by showing that there is a
largest abstract process if and only if the underlying net is conflict-free
with respect to a canonical notion of conflict.
