Multi-Agent Deployment for Visibility Coverage in Polygonal Environments with Holes

This article presents a distributed algorithm for a group of robotic agents with omnidirectional vision to deploy into nonconvex polygonal environments with holes. Agents begin deployment from a common point, possess no prior knowledge of the environment, and operate only under line-of-sight sensing and communication. The objective of the deployment is for the agents to achieve full visibility coverage of the environment while maintaining line-of-sight connectivity with each other. This is achieved by incrementally partitioning the environment into distinct regions, each completely visible from some agent. Proofs are given of (i) convergence, (ii) upper bounds on the time and number of agents required, and (iii) bounds on the memory and communication complexity. Simulation results and description of robust extensions are also included

Performative ontologies. Sociomaterial approaches to researching adult education and lifelong learning

Sociomaterial approaches to researching education, such as those generated by actornetwork theory and complexity theory, have been growing in significance in recent years, both theoretically and methodologically. Such approaches are based upon a performative ontology rather than the more characteristic representational epistemology that informs much research. In this article, we outline certain aspects of sociomaterial sensibilities in researching education, and some of the uptakes on issues related to the education of adults. We further suggest some possibilities emerging for adult education and lifelong learning researchers from taking up such theories and methodologies. (DIPF/Orig.

From isovists to visibility graphs: a methodology for the analysis of architectural space

An isovist, or viewshed, is the area in a spatial environment directly visible from a location within the space. Here we show how a set of isovists can be used to generate a graph of mutual visibility between locations. We demonstrate that this graph can also be constructed without reference to isovists and that we are in fact invoking the more general concept of a visibility graph. Using the visibility graph, we can extend both isovist and current graph-based analyses of architectural space to form a new methodology for the investigation of configurational relationships. The measurement of local and global characteristics of the graph, for each vertex or for the system as a whole, is of interest from an architectural perspective, allowing us to describe a configuration with reference to accessibility and visibility, to compare from location to location within a system, and to compare systems with different geometries. Finally we show that visibility graph properties may be closely related to manifestations of spatial perception, such as way-finding, movement, and space use

Horizontal and Vertical Multiple Implementations in a Model of Industrial Districts

In this paper we discuss strategies concerning the implementation of an agent-based simulation of complex phenomena. The model we consider accounts for population decomposition and interaction in industrial districts. The approach we follow is twofold: on one hand, we implement progressively more complex models using different approaches (vertical multiple implementations); on the other hand, we replicate the agent-based simulation with different implementations using jESOF, JAS and plain C++ (horizontal multiple implementations). By using both different implementation approaches and a multiple implementation strategy, we highlight the benefits that arise when the same model is implemented on radically different simulation environments, comparing the advantages of multiple modeling implementations. Our findings provide some important suggestions in terms of model validation, showing how models of complex systems tend to be extremely sensitive to implementation details. Finally we point out how statistical techniques may be necessary when comparing different platform implementations of a single model.Replication of Models; Model Validation; Agent-Based Simulation

Systemic evil and the international political imagination

In light of the persistence of discourses of atrocity in the post-Holocaust era, and with the resurgence of talk of evil that followed 11 September 2001, it is clear that the idea of evil still possesses a powerful hold upon the modern imagination. Yet, the interplay of evil and the political imagination – in particular, how different images of evil have shaped the discourses and practices of international politics – remains neglected. This article suggests that evil is depicted through three contending images within international politics – evil as individualistic, as statist and as systemic – and their corresponding forms of collective imagination – the juridical, the humanitarian and the political. It argues further that the dominance of the juridical and, to a lesser extent, the humanitarian imagination obscures our ability to imagine and respond to political evils of structural or systemic violence. Drawing on the example of global poverty, this article contends that the ability to portray and critically judge systemic evils in international politics today depends upon enriching our narratives about indefensible atrocities and reimagining our shared political responsibilities for them.PostprintPeer reviewe

How Creative Should Creators be to Optimize the Evolution of Ideas? A Computer Model

There are both benefits and drawbacks to creativity. In a social group it is not necessary for all members to be creative to benefit from creativity; some merely imitate or enjoy the fruits of others' creative efforts. What proportion should be creative? This paper outlines investigations of this question carried out using a computer model of cultural evolution referred to as EVOC (for EVOlution of Culture). EVOC is composed of neural network based agents that evolve fitter ideas for actions by (1) inventing new ideas through modification of existing ones, and (2) imitating neighbors' ideas. The ideal proportion with respect to fitness of ideas is found to depend on the level of creativity of the creative agents. For all levels or creativity, the diversity of ideas in a population is positively correlated with the ratio of creative agents