Talk:Π-calculus

Recent cleanup

I cleaned up the presentation quite a bit. In particular, the presentation of structural congruence had become confusing, and as a consequence the account of the reduction semantics was close to meaningless. I also added a short example that should explain the finer points of name passing. If I find the time at some point, I will add a short section about type systems. HansHuttel 16:50, 5 Jul 2006 (UTC)

Operator precedence

Would it be appropriate to include a table of operator precedence? As a novice, it took me a long time to figure out if ${\overline {x}}\langle z\rangle .P|x(y).Q$ should be parsed as $({\overline {x}}\langle z\rangle .P)|(x(y).Q)$ or ${\overline {x}}\langle z\rangle .(P|x(y).Q)$.

Syntax reference

The reference for the syntax is not consistent with the grammar that is presented. In Milner et al. 1992, there is no bang operator (!P), and recursion is dealt with recursion instead. Replication with !P and structural congruence seems much more common (and convenient) to me.

• (Milner, 2009): The space and motion of communicating agent mentions !P \equiv P | !P, but this is just a comment, not a definition on p. 130, §11.2.

• (Sangiorgi and Walker, 2001): The pi-calculus: a theory of mobile processes defines !P and the structural congruence rule !P \equiv P | !P

• I don't have a copy of (Milner, 1999): Communicating and mobile systems: the pi-calculus --- Maybe this is the first occurence of replication using bang and structural congruence?

Bromind (talk) 12:38, 31 January 2025 (UTC)