  This paper proposes for the first time an algorithm PSpan for mining frequent
complete subnets from a set of Petri nets. We introduced the concept of
complete subnets and the net graph representation. PSpan transforms Petri nets
in net graphs and performs sub-net graph mining on them, then transforms the
results back to frequent subnets. PSpan follows the pattern growth approach and
has similar complexity like gSpan in graph mining. Experiments have been done
to confirm PSpan's reliability and complexity. Besides C/E nets, it applies
also to a set of other Petri net subclasses.
