Relation to Pi Calculus

[David Van Horn]

I've heard that Erlang is essentially an implementation of the untyped pi
calculus.  Is this a fair characterization?  Which variant of the pi calculus
most closely resembles Erlang (eg, asynchronous pi, distributed pi, seal,
join, etc.)?  Could someone provide examples of Erlang primitives that closely
rememble the pi calculus primitives: input, output, and restriction?  Does a
formal semantics of core Erlang exist, and if so where?

Thanks in advance.

-d