Analyzing and reducing simultaneous firing in signal-event nets

Signal-event nets provide a modular modeling technique based on Petri nets. Actions of a module can be activated or can be prevented by another module through condition arcs. One-sided synchronization of modules is done by signal-events, which cause the execution of actions in steps. But due to condition arcs and signal-events simultaneous firing of steps may lead to markings, which are not reachable by conventional sequential interleaving. We give a criterion, in which situations simultaneous firing of steps can be safely omitted, without missing reachable markings.