Expressiveness of concurrent intensionality.

The expressiveness of communication primitives has been explored in a common framework based on the π -calculus by considering four features: synchronism (asynchronous vs synchronous), arity (monadic vs polyadic data), communication medium (shared dataspaces vs channel-based), and pattern-matching (binding to a name vs testing name equality). Here pattern-matching is generalised to account for terms with internal structure such as in recent calculi like Spi calculi, Concurrent Pattern Calculus and Psi calculi. This paper explores intensionality , a feature that extends pattern-matching to allow communication primitives to interact by also matching on the structure of terms. By means of possibility/impossibility of encodings, this paper shows that intensionality alone can encode synchronism, arity, communication-medium, and pattern-matching, yet no combination of these without intensionality can encode any intensional language. Further, some languages may also be non-linear, where two inputs must be equal to allow interaction. This paper also explores all the relations between linear and non-linear variations of the above languages. [ABSTRACT FROM AUTHOR]