Playing with Bisimulation in Erlang

Abstract

Erlang is a functional and concurrent programming language. The aim of this paper is to investigate basic properties of the Erlang concurrency model, which is based on asynchronous communication through mailboxes accessed via pattern matching. To achieve this goal, we consider Core Erlang (which is an intermediate step in Erlang compilation) and we define, on top of its operational semantics, an observational semantics following the approach used to define asynchronous bisimulation for the π-calculus. Our work allows us to shed some light on the management of process identifiers in Erlang, different from the various forms of name mobility already studied in the literature. In fact, we need to modify standard definitions to cope with such specific features of Erlang.

A Proof Assistant Based Formalisation of Core Erlang

“…In order to reuse existing results, we have reviewed the extensive related work on formalisations of both Erlang [6,7,9,15] and Core Erlang [5,8,[10][11][12][13][14], and tried to incorporate ideas from all of these sources. We have decided to build the formalisation of Core Erlang as a stepping stone toward the definition of the entire Erlang language.…”

A Proof Assistant Based Formalisation of a Subset of Sequential Core Erlang

“…[11] describes function applications only for named functions. There is another notable difference in the existing formalisations from the syntactic point of view: some define values as a subclass of expressions by representing them as a distinct syntactic category [6,7,15,18], while others define values as "ground patterns" [11][12][13]16], that is as a subset of patterns. Both approaches have their advantages and disadvantages, and we discuss this question in more detail in Section 3.…”

“…We principally used the work by Lanese et al on defining reversible semantics for Erlang [11][12][13]16], by defining a language "basically equivalent to a subset of Core Erlang" [16]. Although they do not take Core Erlang functions and their closures into consideration (except for top-level functions), which we needed to define from scratch, their work proved to be a good starting point for defining a big-step operational semantics.…”

“…al. [11][12][13]16]) or to expressions, as in the Erlang formalisations and in the work of Neuhäußer et. al.…”

“…We also note that this big-step definition has been partly based on the smallstep definition introduced by Lanese [11,13], Nishida [16], and Neuhasser [15] and in some aspects on the big-step semantics in Focaltest [3] and de Angelis' symbolic evaluation [5]. In addition, for most of the language elements discussed, an informal definition is available in the language specification [4].…”