Generalized Symmetry Breaking Tasks and Nondeterminism in Concurrent Objects

Abstract

Processes in a concurrent system need to coordinate using an underlying shared memory or a message-passing system in order to solve agreement tasks such as, for example, consensus or set agreement. However, coordination is often needed to break the symmetry of processes that are initially in the same state---for example, to get exclusive access to a shared resource, to get distinct names, or to elect a leader. This paper introduces and studies the family of generalized symmetry breaking (GSB) tasks, which includes election, renaming, and many other symmetry breaking tasks, and studies how nondeterminism properties of objects solving tasks affects the computability power of GSB tasks. The aim is to develop the understanding of symmetry breaking tasks and their relation with agreement tasks and to study nondeterminism properties of objects solving tasks and how these properties affect the computability power of symmetry breaking tasks. Among various results characterizing the family of GSB tasks, it is show...