4,766 research outputs found
Anisotropic selection in cellular genetic algorithms
In this paper we introduce a new selection scheme in cellular genetic
algorithms (cGAs). Anisotropic Selection (AS) promotes diversity and allows
accurate control of the selective pressure. First we compare this new scheme
with the classical rectangular grid shapes solution according to the selective
pressure: we can obtain the same takeover time with the two techniques although
the spreading of the best individual is different. We then give experimental
results that show to what extent AS promotes the emergence of niches that
support low coupling and high cohesion. Finally, using a cGA with anisotropic
selection on a Quadratic Assignment Problem we show the existence of an
anisotropic optimal value for which the best average performance is observed.
Further work will focus on the selective pressure self-adjustment ability
provided by this new selection scheme
Credit Assignment in Adaptive Evolutionary Algorithms
In this paper, a new method for assigning credit to search\ud
operators is presented. Starting with the principle of optimizing\ud
search bias, search operators are selected based on an ability to\ud
create solutions that are historically linked to future generations.\ud
Using a novel framework for defining performance\ud
measurements, distributing credit for performance, and the\ud
statistical interpretation of this credit, a new adaptive method is\ud
developed and shown to outperform a variety of adaptive and\ud
non-adaptive competitors
Evidence of coevolution in multi-objective evolutionary algorithms
This paper demonstrates that simple yet important characteristics of coevolution can occur in evolutionary algorithms when only a few conditions are met. We find that interaction-based fitness measurements such as fitness (linear) ranking allow for a form of coevolutionary dynamics that is observed when 1) changes are made in what solutions are able to interact during the ranking process and 2) evolution takes place in a multi-objective environment. This research contributes to the study of simulated evolution in a at least two ways. First, it establishes a broader relationship between coevolution and multi-objective optimization than has been previously considered in the literature. Second, it demonstrates that the preconditions for coevolutionary behavior are weaker than previously thought. In particular, our model indicates that direct cooperation or competition between species is not required for coevolution to take place. Moreover, our experiments provide evidence that environmental perturbations can drive coevolutionary processes; a conclusion that mirrors arguments put forth in dual phase evolution theory. In the discussion, we briefly consider how our results may shed light onto this and other recent theories of evolution
Migrants Selection and Replacement in Distributed Evolutionary Algorithms for Dynamic Optimization
Many distributed systems (task scheduling, moving priorities, changing mobile environments, ...) can be linked as Dynamic Optimization Problems (DOPs), since they require to pursue an optimal value that changes over time. Consequently, we have focused on the utilization of Distributed Genetic Algorithms (dGAs), one of the domains still to be investigated for DOPs. A dGA essentially decentralizes the population in islands which cooperate through migrations of individuals. In this article, we analyze the effect of the migrants selection and replacement on the performance of the dGA for DOPs. Quality and distance based criteria are tested using a comprehensive set of benchmarks. Results show the benefits and drawbacks of each setting in dynamic optimization.Universidad de Málaga. Proyecto roadME (TIN2011-28194). Programa de movilidad de la AUIP
Mergers and acquisitions transactions strategies in diffusion - type financial systems in highly volatile global capital markets with nonlinearities
The M and A transactions represent a wide range of unique business
optimization opportunities in the corporate transformation deals, which are
usually characterized by the high level of total risk. The M and A transactions
can be successfully implemented by taking to an account the size of
investments, purchase price, direction of transaction, type of transaction, and
using the modern comparable transactions analysis and the business valuation
techniques in the diffusion type financial systems in the finances. We
developed the MicroMA software program with the embedded optimized
near-real-time artificial intelligence algorithm to create the winning virtuous
M and A strategies, using the financial performance characteristics of the
involved firms, and to estimate the probability of the M and A transaction
completion success. We believe that the fluctuating dependence of M and A
transactions number over the certain time period is quasi periodic. We think
that there are many factors, which can generate the quasi periodic oscillations
of the M and A transactions number in the time domain, for example: the stock
market bubble effects. We performed the research of the nonlinearities in the M
and A transactions number quasi-periodic oscillations in Matlab, including the
ideal, linear, quadratic, and exponential dependences. We discovered that the
average of a sum of random numbers in the M and A transactions time series
represents a time series with the quasi periodic systematic oscillations, which
can be finely approximated by the polynomial numbers. We think that, in the
course of the M and A transaction implementation, the ability by the companies
to absorb the newly acquired knowledge and to create the new innovative
knowledge bases, is a key predeterminant of the M and A deal completion success
as in Switzerland.Comment: 160 pages, 9 figures, 37 table
Complex and dynamic population structures: synthesis, open questions, and future directions
The population structure of an evolutionary algorithm influences the dissemination and mixing of advantageous alleles, and therefore affects search performance. Much recent attention has focused on the analysis of complex population structures, characterized by heterogeneous connectivity distributions, non-trivial clustering properties, and degree-degree correlations. Here, we synthesize the results of these recent studies, discuss their limitations, and highlight several open questions regarding (1) unsolved theoretical issues and (2) the practical utility of complex population structures for evolutionary search. In addition, we will discuss an alternative complex population structure that is known to significantly influence dynamical processes, but has yet to be explored for evolutionary optimization. We then shift our attention toward dynamic population structures, which have received markedly less attention than their static counterparts. We will discuss the strengths and limitations of extant techniques and present open theoretical and experimental questions and directions for future research. In particular, we will focus on the prospects of "active linking,” wherein edges are dynamically rewired according to the genotypic or phenotypic properties of individuals, or according to the success of prior inter-individual interaction
The prebiotic evolutionary advantage of transferring genetic information from RNA to DNA.
In the early 'RNA world' stage of life, RNA stored genetic information and catalyzed chemical reactions. However, the RNA world eventually gave rise to the DNA-RNA-protein world, and this transition included the 'genetic takeover' of information storage by DNA. We investigated evolutionary advantages for using DNA as the genetic material. The error rate of replication imposes a fundamental limit on the amount of information that can be stored in the genome, as mutations degrade information. We compared misincorporation rates of RNA and DNA in experimental non-enzymatic polymerization and calculated the lowest possible error rates from a thermodynamic model. Both analyses found that RNA replication was intrinsically error-prone compared to DNA, suggesting that total genomic information could increase after the transition to DNA. Analysis of the transitional RNA/DNA hybrid duplexes showed that copying RNA into DNA had similar fidelity to RNA replication, so information could be maintained during the genetic takeover. However, copying DNA into RNA was very error-prone, suggesting that attempts to return to the RNA world would result in a considerable loss of information. Therefore, the genetic takeover may have been driven by a combination of increased chemical stability, increased genome size and irreversibility
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