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A common assumption in sensor networks is that the sensors are located according to a uniform random distribution. In this paper we show that uniform random points on the two dimensional unit square are almost a "grid". In particular, for a synchronous geographic sensor network we show how to emulate any grid protocol on random sensor networks, with high probability. This suggests the following framework. In order to solve a problem on a random sensor network we solve the same problem on the grid. Then we use our emulation to make the obtained solution suitable for random sensor network. We analyze the cost of the emulation in terms of consumed energy and time. Finally we provide three examples that illustrate our method. Keywords: Routing, Scheduling, MAC-layer, Collisions, Grid. [ABSTRACT FROM AUTHOR]

The Minimum Energy Broadcast Routing problem was extensively studied during the last years. Given a sample space where wireless devices are distributed, the aim is to perform the broadcast pattern of communication from a given source while minimizing the total energy consumption. While many papers deal with the 2-dimensional case where the sample space is given by a flat area, few results are known about the more interesting and practical 3-dimensional case. In this paper we study such a case and we present a tighter analysis of the minimum spanning tree heuristic in order to considerably decrease its approximation factor from the known 26 to roughly 18.8. This decreases the gap with the known lower bound of 12 given by the so called kissing number. [ABSTRACT FROM AUTHOR]

The paper deals with one of the most studied problems during the last years in the field of wireless communications in Ad-Hoc networks. The problem consists in reducing the total energy consumption of wireless radio stations randomly spread on a given area of interest to perform the basic pattern of communication given by the Broadcast. Recently an almost tight 6.33-approximation of the Minimum Spanning Tree heuristic has been proved [8]. While such a bound is theoretically close to optimum compared to the known lower bound of 6 [10], there is an evident gap with practical experimental results. By extensive experiments, proposing a new technique to generate input instances and supported by theoretical results, we show how the approximation ratio can be actually considered close to 4 for a "real world" set of instances, that is, instances with a number of nodes more representative of practical purposes. [ABSTRACT FROM AUTHOR]

We consider the problem of determining constructions with an asymptotically optimal oblivious diameter in small world graphs under the Kleinberg's model. In particular, we give the first general lower bound holding for any monotone distance distribution, that is induced by a monotone generating function. Namely, we prove that the expected oblivious diameter is Ω (log 2n) even on a path of n nodes. We then focus on deterministic constructions and after showing that the problem of minimizing the oblivious diameter is generally intractable, we give asymptotically optimal solutions, that is with a logarithmic oblivious diameter, for paths, trees and Cartesian products of graphs, including d-dimensional grids for any fixed value of d. [ABSTRACT FROM AUTHOR]

Over the last decade electoral engineers have become increasingly cognisant of three important facts that affect worldwide electoral institutions. First, several established democracies such as Israel, Italy, Japan, New Zealand and Venezuela undertook major electoral reforms. Second, the process of democratisation in formerly communist countries brought about constitutional reforms where the design of new systems of representation is the central concern. Third, mixed-member electoral (MM) systems have been the choice of the vast majority of countries implementing electoral reform. [ABSTRACT FROM AUTHOR]

In the public choice tradition, politics is seen as a market activity in which individual preferences are revealed and translated into public policies through a ‘production' process. In this framework, a sequence of elections may be considered as a repeated game in which the preferences of society are expressed and find representation (Ordeshook, 1997). The expression and implementation of societal preferences and the production of implied policies are guaranteed by the repeated nature of the game. The market where this game is played is the electoral market. [ABSTRACT FROM AUTHOR]