A new local structure called a second-order structure was proposed to generate a new class of nets called synchronized choice nets (SNC). SNC covers well-behaved free choice nets. Reachability is no longer P-Space hard problem, but can be solved with polynomial time complexity. How to extend them to non-SNC and its application to deadlock detection in flexible manufacturing systems are discussed.
IEEE transactions on systems, man, and cybernetics.Part B,35(6), 1203-1213