Time and Cybernetics

Basic meanings of the term "time" can be introduced in the following complementary couples: physical/logical, absolute/relative, global/local. To be more precise, we consider an event domain, E, and a time domain, T, such that instead of viewing the precedence relation "to causally affect" on events we use members of a time domain to mark the members of the event domain to introduce a temporal order. Whereas synchronous models of computation regard all concurrent activities happen in a lock-step, asynchronous models are not restricted in this sense. They can be treated as interleaving models of computation, which sequentialize simultaneous actions non-deterministically, or as true concurrency models of computation, which impose only a partial ordering between actions.