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Liam Walsh

Publications and source records attributed to Liam Walsh.

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Repeated and incontrovertible collective action failure leads to protester disengagement and radicalisation

Protest is ubiquitous in the 21st Century and the people who participate in such movements do so because they seek to bring about social change. However, social change takes time and involves repeated interactions between individual protesters, social movements and the authorities to whom they appeal for change. These complexities of time and scale have frustrated efforts to isolate the conditions that foster an enduring movement, on the one hand, and the adoption of more radical (unconventional, unacceptable) tactics on the other. Here, we present a novel, theoretically informed and empirically evidenced, agent-based model of collective action that provides a unified framework to address these dual challenges. We model ~10,000 iterations within a simulated society and show that where an authority is responsive, and protesters can (cognitively and/or socially) contest the failure of their movement, a moderate conventional movement prevails. Conversely, where an authority repeatedly and incontrovertibly fails the movement, the population disengages but becomes radicalised (latent radicalism). This latter finding, whereby the whole population is disengaged but prepared to use radical methods to bring about social change, likely reflects the febrile pre-cursor state to sudden, revolutionary change. Results highlight the potential for simulations to reveal emergent, as-yet under-theorized, phenomena.

cs.SI

Decentralised adaptive-gain control for eliminating epidemic spreading on networks

This paper considers the classical Susceptible--Infected--Susceptible (SIS) network epidemic model, which describes a disease spreading through $n$ nodes, with the network links governing the possible transmission pathways of the disease between nodes. We consider feedback control to eliminate the disease in scenarios where the disease would otherwise persist in an uncontrolled network. We propose a family of decentralised adaptive-gain control algorithms, in which each node has a control gain that adaptively evolves according to a differential equation, independent of the gains of other nodes. The adaptive gain is applied multiplicatively to either decrease the infection rate or increase the recovery rate. To begin, we assume all nodes are controlled, and prove that both infection rate control and recovery rate control algorithms eliminate the disease with the limiting gains being positive and finite. Then, we consider the possibility of controlling a subset of the nodes, for both the infection rate control and recovery rate control. We first identify a necessary and sufficient condition for the existence of a subset of nodes, which if controlled would result in the elimination of the disease. For a given network, there may exist several such viable subsets, and we propose an iterative algorithm to identify such a subset. Simulations are provided to demonstrate the effectiveness of the various proposed controllers.

eess.SY

A General Architecture for Client-Agnostic Hybrid Model Editors as a Service

In this paper, we propose a general architecture for designing language servers for hybrid modeling languages, that is, modeling languages that contain both textual and graphical representations. The architecture consists of a textual language server, a graphical language server, and a client that communicates with the two servers. The servers are implemented using the Language Server Protocol (LSP) and the Graphical Language Server Protocol (GLSP) and are based on a shared abstract syntax of the hybrid language. This means that only static resources need to be common between the graphical and textual language servers. The servers' separation allows each to be developed and maintained independently, while also enabling forward-compatibility with their respective dependencies. We describe a prototype implementation of our architecture in the form of a hybrid editor for the UML-RT language. The evaluation of the architecture via this prototype gives us useful insight into further generalization of the architecture and the way it is used. We then sketch a suitable extension of the architecture to enable support for multiple diagram types and, thus, multiple graphical views.

cs.SE