master-degree-notes/Concurrent Systems/notes/12 - bastaaaaaaaa.md

• Up to now, we have considered non-deterministic processes

• Two main features are missing for modeling a concurrent system:

  • Simultaneous execution of processes
  • Inter-process interaction

• Solutions adopted:

  • Parallel composition, with interleaving semantics
  • Producer/consumer paradigm

Given a set of names N (that denote events)

• a (∈ N) denotes consumption of event a
• \bar{a} (for a ∈ N) denotes production of event a
• a and \bar{a} are complementary actions: they let two parallel processes synchronize on the event a

When two processes synchronize, an external observer has no way of understanding what is happening in the system

• synchronization is not observable from the outside; it produces a special ‘silent’ action, that we denote with τ

The set of actions we shall consider is: