What is a 'Good' Encoding of Guarded Choice?

Uwe Nestmann
1997 Electronical Notes in Theoretical Computer Science  
The -calculus with synchronous output and mixed-guarded choices is strictly more expressive than the -calculus with asynchronous output and no choice. As a corollary, P alamidessi recently proved that there is no fully compositional encoding from the former into the latter that preserves divergence-freedom and symmetries. This paper shows that there are nevertheless'good' encodings between these calculi. In detail, we present a series of encodings for languages with (1) input-guarded choice,
more » ... both input-and output-guarded choice, and (3) mixed-guarded choice, and investigate them with respect to compositionality and divergence-freedom. The rst and second encoding satisfy all criteria, but various'good' candidates for the third encoding|inspired by an existing distributed implementation|invalidate one or the other criterion. While essentially con rming Palamidessi's result, our study suggests that the combination of strong compositionality and divergence-freedom is too strong for more practical purposes.
doi:10.1016/s1571-0661(05)80474-8 fatcat:toc36ecepnh2znenleb73aj2te