Northern Ireland’s 1968 at 50: agonism and protestant perspectives on civil rights

2018 marked the fiftieth anniversary of the seminal events of Northern Ireland’s 1968: a milestone offering up an opportunity to reassess a pivotal moment in the province’s recent past. This article will argue that the civil rights period has fitted into a common model of the past being used to perpetuate the divisions at the heart of Northern Irish society. It will go on to demonstrate how an innovative methodological and theoretical approach, based on oral history, education and – most crucially – agonism, has facilitated the unearthing and integration of complex and hitherto marginalised Ulster Protestant perspectives

A Hierarchical Membership Protocol for Synchronous Distributed Systems

. A membership service for a synchronous distributed computer system is described. The system is assumed to be composed of groups in which a relatively frequent message exchange occurs. A hierarchy of connected groups constitutes a connected network. The membership service protocol reflects this hierarchical structure. The protocol tolerates timing, omission and crash failures. Time-bounds are specified in which additions (removals) of processors to (from) the system are known to all participating processors. keywords: membership service, distributed algorithm, fault tolerance, hierarchical system, synchronous system. 1 Introduction The construction of a service that determines the presence of correct processors in a distributed system, commonly known as the membership service, is regarded as a fundamental problem in distributed systems. Once solved, it allows the solution of many other problems based upon its availability. Three advantages of membership are: -- (i) efficie..

Self-stabilizing mutual exclusion on directed graphs

This paper investigates the complexity of self-stabilizing mutual exclusion protocols for distributed systems, where processors communicate through shared memory according to a strongly connected directed communication graph. Tchuente's approach of covering a network with one directed cycle is taken as point of departure. This protocol requires O(n^{2n) states per processor together with some preprocessing. By coalescing states a protocol requiring only $O(n^2)$ states per processor---still requiring preprocessing---is derived. Finally two protocols based on spanning trees are considered. Combining these protocols with a self-stabilizing spanning tree protocol yields two $O(n^3 m)$---where $m$ is the maximal degree of a processor---states per processor protocols that require knowledge of processor identities. This report concludes with a full proof of the coalesced states protocol in Lamport's Temporal Logic of Actions