%0 Conference Paper %B IEEE Congress on Evolutionary Computation, 2012. CEC 2012. (IEEE World Congress on Computational Intelligence) %D 2012 %T Density Based Projection Pursuit Clustering %A S. K. Tasoulis %A M. G. Epitropakis %A V. P. Plagianakos %A D. K. Tasoulis %X Clustering of high dimensional data is a very important task in Data Mining. In dealing with such data, we typically need to use methods like Principal Component Analysis and Projection Pursuit, to find interesting lower dimensional directions to project the data and hence reduce their dimensionality in a manageable size. In this work, we propose a new criterion of direction interestingness, which incorporates information from the density of the projected data. Subsequently, we utilize the Differential Evolution algorithm to perform optimization over the space of the projections and hence construct a new hierarchical clustering algorithmic scheme. The new algorithm shows promising performance over a series of real and simulated data. %B IEEE Congress on Evolutionary Computation, 2012. CEC 2012. (IEEE World Congress on Computational Intelligence) %C Brisbane, Australia %8 June %G eng %R 10.1109/CEC.2012.6253006 %0 Book Section %B Artificial Intelligence: Theories and Applications %D 2012 %T Tracking Differential Evolution Algorithms: An Adaptive Approach through Multinomial Distribution Tracking with Exponential Forgetting %A M. G. Epitropakis %A D. K. Tasoulis %A N. G. Pavlidis %A V. P. Plagianakos %A M. N. Vrahatis %E Ilias Maglogiannis %E Vassilis P. Plagianakos %E Ioannis Vlahavas %X Several Differential Evolution variants with modified search dynamics have been recently proposed, to improve the performance of the method. This work borrows ideas from adaptive filter theory to develop an “online” algorithmic adaptation framework. The proposed framework is based on tracking the parameters of a multinomial distribution to reflect changes in the evolutionary process. As such, we design a multinomial distribution tracker to capture the successful evolution movements of three Differential Evolution algorithms, in an attempt to aggregate their characteristics and their search dynamics. Experimental results on ten benchmark functions and comparisons with five state-of-the-art algorithms indicate that the proposed framework is competitive and very promising. %B Artificial Intelligence: Theories and Applications %S Lecture Notes in Computer Science %I Springer Berlin / Heidelberg %V 7297 %P 214-222 %@ 978-3-642-30447-7 %G eng %R 10.1007/978-3-642-30448-4_27 %0 Conference Paper %B IEEE Congress on Evolutionary Computation, 2012. CEC 2012. (IEEE World Congress on Computational Intelligence) %D 2012 %T Tracking Particle Swarm Optimizers: An adaptive approach through multinomial distribution tracking with exponential forgetting %A M. G. Epitropakis %A D. K. Tasoulis %A N. G. Pavlidis %A V. P. Plagianakos %A M. N. Vrahatis %X An active research direction in Particle Swarm Optimization (PSO) is the integration of PSO variants in adaptive, or self-adaptive schemes, in an attempt to aggregate their characteristics and their search dynamics. In this work we borrow ideas from adaptive filter theory to develop an “online” algorithm adaptation framework. The proposed framework is based on tracking the parameters of a multinomial distribution to capture changes in the evolutionary process. As such, we design a multinomial distribution tracker to capture the successful evolution movements of three PSO variants. Extensive experimental results on ten benchmark functions and comparisons with five state-of-the-art algorithms indicate that the proposed framework is competitive and very promising. On the majority of tested cases, the proposed framework achieves substantial performance gain, while it seems to identify accurately the most appropriate algorithm for the problem at hand. %B IEEE Congress on Evolutionary Computation, 2012. CEC 2012. (IEEE World Congress on Computational Intelligence) %C Brisbane, Australia %8 June %G eng %R 10.1109/CEC.2012.6256425 %0 Journal Article %J IEEE Transactions on Evolutionary Computation %D 2011 %T Enhancing Differential Evolution Utilizing Proximity-based Mutation Operators %A M. G. Epitropakis %A D. K. Tasoulis %A N. G. Pavlidis %A V. P. Plagianakos %A M. N. Vrahatis %X Differential evolution is a very popular optimization algorithm and considerable research has been devoted to the development of efficient search operators. Motivated by the different manner in which various search operators behave, we propose a novel framework based on the proximity characteristics among the individual solutions as they evolve. Our framework incorporates information of neighboring individuals, in an attempt to efficiently guide the evolution of the population toward the global optimum, without sacrificing the search capabilities of the algorithm. More specifically, the random selection of parents during mutation is modified, by assigning to each individual a probability of selection that is inversely proportional to its distance from the mutated individual. The proposed framework can be applied to any mutation strategy with minimal changes. In this paper, we incorporate this framework in the original differential evolution algorithm, as well as other recently proposed differential evolution variants. Through an extensive experimental study, we show that the proposed framework results in enhanced performance for the majority of the benchmark problems studied. %B IEEE Transactions on Evolutionary Computation %V 15 %P 99-119 %G eng %R 10.1109/TEVC.2010.2083670