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McMillan has recently proposed a new technique to avoid the state explosion problem in the verification of systems modelled with finite-state Petri nets. The technique requires to construct a finite initial part of the unfolding of the net. McMillan's algorithm for this task may yield initial parts that are larger than necessary (exponentially larger in the(More)
A key problem in mixing operational (e.g., process-algebraic) and declarative (e.g., logical) styles of specification is how to deal with inconsistencies arising when composing processes under conjunction. This article introduces a conjunction operator on labelled transition systems capturing the basic intuition of " a and b = false " , and considers a(More)
We investigate the notion of fair testing, a formal testing theory in the style of De Nicola and Hennessy, where divergences are disregarded as long as there are visible outgoing transitions. The usual testing theories, such as the standard model of failure pre-order, do not allow such fair interpretations because of the way in which they ensure their(More)
Petri nets with read arcs are investigated with respect to their unfolding, where read arcs model reading without consuming, which is often more adequate than the destructive-read-and-rewrite modelled with loops in ordinary nets. The paper redeenes the concepts of a branching process and unfolding for nets with read arcs and proves that the set of reachable(More)