Message-passing based concurrent languages are widely used in developing large distributed and coordination systems. This paper presents the buffered $pi$-calculus --- a variant of the $pi$-calculus where channel names are classified into buffered an
d unbuffered: communication along buffered channels is asynchronous, and remains synchronous along unbuffered channels. We show that the buffered $pi$-calculus can be fully simulated in the polyadic $pi$-calculus with respect to strong bisimulation. In contrast to the $pi$-calculus which is hard to use in practice, the new language enables easy and clear modeling of practical concurrent languages. We encode two real-world concurrent languages in the buffered $pi$-calculus: the (core) Go language and the (Core) Erlang. Both encodings are fully abstract with respect to weak bisimulations.
Program equivalence in linear contexts, where programs are used or executed exactly once, is an important issue in programming languages. However, existing techniques like those based on bisimulations and logical relations only target at contextual e
quivalence in the usual (non-linear) functional languages, and fail in capturing non-trivial equivalent programs in linear contexts, particularly when non-determinism is present. We propose the notion of linear contextual equivalence to formally characterize such program equivalence, as well as a novel and general approach to studying it in higher-order languages, based on labeled transition systems specifically designed for functional languages. We show that linear contextual equivalence indeed coincides with trace equivalence - it is sound and complete. We illustrate our technique in both deterministic (a linear version of PCF) and non-deterministic (linear PCF in Moggis framework) functional languages.
