Operational equivalence for interaction nets

The notion of contextual (or operational) equivalence is fundamental in the theory of programming languages. By setting up a notion of bisimilarity, and showing that it coincides with contextual equivalence, one obtains a simple coinductive proof technique for showing that two programs are equivalent in all contexts. In this paper we apply these (now standard) techniques to interactions nets, a graphical programming language characterized by local reduction. This work generalizes previous studies of operational equivalence in typed interaction nets since it can be applied to untyped systems, thus all systems of interaction nets are captured.