Abstract. We present the ω-calculus, a process calculus for formally modeling and reasoning about Mobile Ad Hoc Wireless Networks (MANETs) and their protocols. The ω-calculus naturally captures essential characteristics of MANETs, including the ability of a MANET node to broadcast a message to any other node within its physical transmission range (and no others), and to move in and out of the transmission range of other nodes in the network. A key feature of the ω-calculus is the separation of a node’s communication and computational behavior, described by an ω-process, from the description of its physical transmission range, referred to as an ω-process interface. Our main technical results are as follows. We give a formal operational semantics of the ω-calculus in terms of labeled transition systems and show that the state reachability problem is decidable for finite-control ω-processes. We also prove that the ω-calculus is a conservative extension of the π-calculus, and that late bisimulation (appropriately lifted from the π-calculus to the ω-calculus) is a congruence. Congruence results are also established for a weak version of late bisimulation, which abstracts away from two types of internal actions: τ-actions, as in the π-calculus, and µ-actions, signaling node movement. Finally, we illustrate the practical utility of the calculus by developing and analyzing a formal model of a leader-election protocol for MANETs. 1

Abstract. In this paper we present an automatic verification technique for parameterized systems where the subsystem behavior is modeled using the πcalculus. At its core, our technique treats each process instance in a system as a property transformer. Given a property ϕ that we want to verify of an N-process system, we use a partial model checker to infer the property ϕ ′ (stated as a formula in a sufficiently rich logic) that must hold of an (N − 1)-process system. If the sequence of formulas ϕ, ϕ ′,...thus constructed converges, and the limit is satisfied by the deadlocked process, we can conclude that the N-process system satisfies ϕ. To this end, we develop a partial model checker for the π-calculus that uses an expressive value-passing logic as the property language. We also develop a number of optimizations to make the model checker efficient enough for routine use, and a light-weight widening operator to accelerate convergence. We demonstrate the effectiveness of our technique by using it to verify properties of a wide variety of parameterized systems that are beyond the reach of existing techniques. 1