# Strong bisimulation for explicit fusions

Lucian Wischik, Philippa Gardner.
Submitted for publication.

## Abstract.

In the pi calculus, the
various definitions of (strong) congruence yield different
relations. In one widely-studied variant of the pi calculus, the
asynchronous, it turns out that they coincide. We show that they
also coincide in a different variant, the *explicit fusion
calculus*.

The important consequence of adding explicit fusions to a calculus
is that an explicit fusion in parallel with a term can effect a
substitution. This means that parallel contexts become as
discriminating as arbitrary contexts, and that *open
bisimulation* is more natural for the explicit fusion calculus
than it was for the pi calculus.