Deadlock Freedom for Asynchronous and Cyclic Process Networks (Extended Version)

Establishing the deadlock-freedom property for message-passing processes is an important and challenging problem. This paper considers verification techniques based on behavioral type systems to address the relevant case of processes that communicate asynchronously in cyclic process networks and are governed by session types. We present APCP, a typed process framework for deadlock-freedom which supports asynchronous communication, delegation, recursion, and a form of process composition that enables specifying cyclic process networks. We discuss the main decisions involved in the design of APCP and establish its essential results.