Incomparability of Gamma and Linda. Software Engineering

摘要

We compare Gamma and Linda, two of the most prominent coordination languages211u001ebased on generative communication via a shared data space. In Gamma computation 211u001eis obtained by applying multiset rewriting rules, reminiscent of the way chemical 211u001ereactions happen in a solution. On the other hand, Linda permits interprocess 211u001ecommunication by means of the creation and consumption of shared data. Also a non-211u001eblocking input operator is allowed: it terminates indicating if the required 211u001edatum has been consumed or it is not actually available. We first recall two 211u001esimple calculi based on Gamma and Linda coordination models. Even if both the 211u001elanguages are Turing powerful, we show that their expressive power is not 211u001ecomparable; in particular, we prove that there exists no program distribution 211u001epreserving encoding of one language in the other that respects at least the input-211u001eoutput behavior.