This properly extends other mainstream representations of concurrent behavior such as event structures, yet is defined more simply. It admits an intrinsic notion of duality that permits processes to be viewed as either schedules or automata. Its algebraic structure is essentially that of linear logic, with its morphisms being consequence-preserving renamings of propositions, and with its operations forming the core of a natural concurrent programming language. It was in their work that the idea of considering such structures as a model of concurrency arose.
Gates accept concurrent behavior.
IEEE Symp. on Foundations of Comp. Doc 105 Theoretical Computer Science - Nielsen, Plotkin et al.