  In this paper we propose two new subclasses of Petri nets with resets, for
which the reachability and coverability problems become tractable. Namely, we
add an acyclicity condition that only applies to the consumptions and
productions, not the resets. The first class is acyclic Petri nets with resets,
and we show that coverability is PSPACE-complete for them. This contrasts the
known Ackermann-hardness for coverability in (not necessarily acyclic) Petri
nets with resets. We prove that the reachability problem remains undecidable
for acyclic Petri nets with resets. The second class concerns workflow nets, a
practically motivated and natural subclass of Petri nets. Here, we show that
both coverability and reachability in acyclic workflow nets with resets are
PSPACE-complete. Without the acyclicity condition, reachability and
coverability in workflow nets with resets are known to be equally hard as for
Petri nets with resets, that being Ackermann-hard and undecidable,
respectively.
