The formal semantics of Erlang is a bit too complicated to be easily understandable. Much of this complication stems from the desire to accurately model the current implementations (Erlang/OTP R11-R14), which include features (and optimizations) developed during more than two decades. The result is a two-tier semantics where systems, and in particular messages, behave differently in a local and a distributed setting. With the introduction of multi-core hardware, multiple run-queues and efficient SMP support, the boundary between local and distributed is diffuse and should ultimately be removed. In this paper we develop a new, much cleaner semantics, for such future implementations of Erlang. We hope that this paper can stimulate some much needed debate regarding a number of poorly understood features of current and future implementations of Erlang.

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In 1982 Dolev, et al. [10] presented an O(nlogn) unidirectional distributed algorithm for the circular extrema-finding (or leader-election) problem. At the same time Peterson came up with a nearly identical solution. In this paper, we bring the correctness of this algorithm to a completely formal level. This relatively small protocol, which can be described on half a page, requires a rather involved proof for guaranteeing that it behaves well in all possible circumstances. To our knowledge, this is one of the more advanced case-studies in formal verification based on process algebra.

Erlang is a functional programming language with support for concurrency and message passing communication that is used at Ericsson for developing telecommunication applications. We consider the challenge of verifying temporal properties of systems programmed in Erlang with dynamically evolving process structures. To accomplish this a rich verijkation framework for goal-directed, proof systembased verification is used. This paper investigates the problem of semi-automating the verification task by identifying the proof parameters crucial for successful proof search.