Verification of Scala Actors

Decidability results on Petri nets: Decidability issues for Petri nets - a survey, by Javier Esparza and Mogens Nielsen, in: Bulletin of the EATCS, 1994. Revised, 1995. Decidability and complexity of petri net problems - an introduction, by Javier Esparza.

Decidability results on Asychronous $\pi$-calculus: On decidability of the control reachability problem in the asynchronous pi-calculus, in: Nordic Journal of Computing, 9(1):70–101, 2002.

Types as Models, and Types as Models Paper PDF

The reference about $\pi$-calculus The polyadic $\pi$-calculus, by Robin Milner.