“…After that, the original idea has been developed (see, for example, [27]) and extended in several different directions, including: other Petri net classes (e.g., bounded pt-nets without loops [6], pt-nets [26], Flip-flop nets [29], nets with inhibitor arcs [8,28], and nets with localities [25]); synthesis modules of implemented tool frameworks (e.g., Petrify [12], ProM [31], VipTool [5], Genet [9], and Rbminer [30]); application areas (e.g., asynchronous VLSI circuits [12,9,30] and workflows [31]); other semantical execution models (e.g., step sequences [19,28], (local) maximal concurrency [25], and firing policies [14]); and specification formalisms other than transition systems (e.g., languages [13] and scenarios [5]). More details concerning the importance and long term impact of the region concept can be found in the monograph [3].…”