Search

When search methods are being designed it is very important to know which parameters have the greatest influence on the behaviour and performance of the algorithm. To this end, algorithm parameters are commonly calibrated by means of either theoretic analysis or intensive experimentation. When undertaking a detailed statistical analysis of the influence of each parameter, the designer should pay attention mostly to the parameters that are statistically significant. In this paper the ANOVA (ANalysis Of the VAriance) method is used to carry out an exhaustive analysis of a simulated annealing based method and the different parameters it requires. Following this idea, the significance and relative importance of the parameters regarding the obtained results, as well as suitable values for each of these, were obtained using ANOVA and post-hoc Tukey HSD test, on four well known function optimization problems and the likelihood function that is used to estimate the parameters involved in the lognormal diffusion process. Through this statistical study we have verified the adequacy of parameter values available in the bibliography using parametric hypothesis tests.

In a connected world, spare CPU cycles are up for grabs, if you only make its obtention easy enough. In this paper we present a distributed evolutionary computation system that uses the computational capabilities of the ubiquituous web browser. Using Asynchronous Javascript and JSON (Javascript Object Notation, a serialization protocol) allows anybody with a web browser (that is, mostly everybody connected to the Internet) to participate in a genetic algorithm experiment with little effort, or none at all. Since, in this case, computing becomes a social activity and is inherently impredictable, in this paper we will explore the performance of this kind of virtual computer by solving simple problems such as the Royal Road function and analyzing how many machines and evaluations it yields. We will also examine possible performance bottlenecks and how to solve them, and, finally, issue some advice on how to set up this kind of experiments to maximize turnout and, thus, performance., Comment: arXiv admin note: text overlap with arXiv:cs/0701115

In this work we propose a fine grained approach with self-adaptive migration rate for distributed evolutionary computation. Our target is to gain some insights on the effects caused by communication when the algorithm scales. To this end, we consider a set of basic topologies in order to avoid the overlapping of algorithmic effects between communication and topological structures. We analyse the approach viability by comparing how solution quality and algorithm speed change when the number of processors increases and compare it with an Island model based implementation. A finer-grained approach implies a better chance of achieving a larger scalable system; such a feature is crucial concerning large-scale parallel architectures such as Peer-to-Peer systems. In order to check scalability, we perform a threefold experimental evaluation of this model: First, we concentrate on the algorithmic results when the problem scales up to eight nodes in comparison with how it does following the Island model. Second, we analyse the computing time speedup of the approach while scaling. Finally, we analyse the network performance with the proposed self-adaptive migration rate policy that depends on the link latency and bandwidth. With this experimental setup, our approach shows better scalability than the Island model and a equivalent robustness on the average of the three test functions under study., Comment: arXiv admin note: text overlap with arXiv:cs/0703117

Introducing new technologies such as messaging platforms, and the chatbots attached to them, in higher education, is rapidly growing. This introduction entails a careful consideration of the potential opportunities and/or challenges of adopting these tools. Hence, a thorough examination of the teachers' experiences in this discipline can shed light on the effective ways of enhancing students' learning and boosting their progress. In this contribution, we have surveyed the opinions of tertiary education teachers based in Spain (mainly) and Spanish-speaking countries. The focus of these surveys is to collect teachers' feedback about their opinions regarding the introduction of the messaging platforms and chatbots in their classes, understand their needs and to gather information about the various educational use cases where these tools are valuable. In addition, an analysis of how and when teachers' opinions towards the use of these tools can vary across gender, experience, and their discipline of specialisation is presented. The key findings of this study highlight the factors that can contribute to the advancement of the adoption of messaging platforms and chatbots in higher education institutions to achieve the desired learning outcomes.

Mastermind is in essence a search problem in which a string of symbols that is kept secret must be found by sequentially playing strings that use the same alphabet, and using the responses that indicate how close are those other strings to the secret one as hints. Although it is commercialized as a game, it is a combinatorial problem of high complexity, with applications on fields that range from computer security to genomics. As such a kind of problem, there are no exact solutions; even exhaustive search methods rely on heuristics to choose, at every step, strings to get the best possible hint. These methods mostly try to play the move that offers the best reduction in search space size in the next step; this move is chosen according to an empirical score. However, in this paper we will examine several state of the art exhaustive search methods and show that another factor, the presence of the actual solution among the candidate moves, or, in other words, the fact that the actual solution has the highest score, plays also a very important role. Using that, we will propose new exhaustive search approaches that obtain results which are comparable to the classic ones, and besides, are better suited as a basis for non-exhaustive search strategies such as evolutionary algorithms, since their behavior in a series of key indicators is better than the classical algorithms., Comment: 41 pages, to be submitted to Computers and Operations Research

Online proceedings for the first workshop on complex systems in sports; index pointing to the papers that will be presented and discussed in that workshop. The papers deal with sports from a complex systems point of view, and include papers on a network analysis of the performance of the Spanish team in the 2010 world cup and basketball scoring, study of populations of sports fans, try to select attributes for sports forecasting and finally try to analyze the physical condition from the perspective of complexity.

We analyze the pass network among the players of the Spanish team (the world champion in the FIFA World Cup 2010), with the objective of explaining the results obtained from the behavior at the complex network level. The team is considered a network with players as nodes and passes as (directed) edges, and a temporal analysis of the resulting passes network is done, looking at the number of passes, length of the chain of passes, and the centrality of players in the turf. Results of the last three matches indicate that the clustering coefficient of the pass network increases with time, and stays high, indicating possession by Spanish players, which eventually leads to victory, even as the density of the pass network decreases with time., Comment: Paper 6 for the Complex Systems in Sports Workshop 2011 (CS-Sports 2011)

After a proof of concept using Dropbox(tm), a free storage and synchronization service, showed that an evolutionary algorithm using several dissimilar computers connected via WiFi or Ethernet had a good scaling behavior in terms of evaluations per second, it remains to be proved whether that effect also translates to the algorithmic performance of the algorithm. In this paper we will check several different, and difficult, problems, and see what effects the automatic load-balancing and asynchrony have on the speed of resolution of problems., Comment: Paper 4 for the First International Workshop of Distributed Evolutionary computation in Informal Environments