Coinductive Big-Step Semantics for Concurrency

TL;DR

This paper extends coinductive big-step semantics to handle concurrency with shared variables, accurately modeling divergence and observable effects, and provides a constructive metatheory for this framework.

Contribution

It introduces a coinductive big-step semantics framework for concurrent programs with shared variables, capturing divergence and observable effects more precisely.

Findings

Handles divergence properly in concurrent semantics

Models observable effects before divergence

Provides a constructive proof of the semantics' metatheory

Abstract

In a paper presented at SOS 2010, we developed a framework for big-step semantics for interactive input-output in combination with divergence, based on coinductive and mixed inductive-coinductive notions of resumptions, evaluation and termination-sensitive weak bisimilarity. In contrast to standard inductively defined big-step semantics, this framework handles divergence properly; in particular, runs that produce some observable effects and then diverge, are not "lost". Here we scale this approach for shared-variable concurrency on a simple example language. We develop the metatheory of our semantics in a constructive logic.