Pi-calculus

Summary

The $\pi$-calculus is a process calculus in which channel names can themselves be sent along channels. It was introduced by Robin Milner, Joachim Parrow and David Walker as a calculus of mobile processes, whose links can change while they run. Its main step is communication: $\overline{x}\langle y \rangle.P \mid x(z).Q$ becomes $P \mid Q[y/z]$, so the receiver learns the name $y$ and may later use it as a channel. The lambda calculus can be encoded in it, and it is a basic model for concurrent and distributed systems and for session types.