4,605 research outputs found
Adaptive multimodal continuous ant colony optimization
Seeking multiple optima simultaneously, which multimodal optimization aims at, has attracted increasing attention but remains challenging. Taking advantage of ant colony optimization algorithms in preserving high diversity, this paper intends to extend ant colony optimization algorithms to deal with multimodal optimization. First, combined with current niching methods, an adaptive multimodal continuous ant colony optimization algorithm is introduced. In this algorithm, an adaptive parameter adjustment is developed, which takes the difference among niches into consideration. Second, to accelerate convergence, a differential evolution mutation operator is alternatively utilized to build base vectors for ants to construct new solutions. Then, to enhance the exploitation, a local search scheme based on Gaussian distribution is self-adaptively performed around the seeds of niches. Together, the proposed algorithm affords a good balance between exploration and exploitation. Extensive experiments on 20 widely used benchmark multimodal functions are conducted to investigate the influence of each algorithmic component and results are compared with several state-of-the-art multimodal algorithms and winners of competitions on multimodal optimization. These comparisons demonstrate the competitive efficiency and effectiveness of the proposed algorithm, especially in dealing with complex problems with high numbers of local optima
The Dynamics of a Genetic Algorithm for a Simple Learning Problem
A formalism for describing the dynamics of Genetic Algorithms (GAs) using
methods from statistical mechanics is applied to the problem of generalization
in a perceptron with binary weights. The dynamics are solved for the case where
a new batch of training patterns is presented to each population member each
generation, which considerably simplifies the calculation. The theory is shown
to agree closely to simulations of a real GA averaged over many runs,
accurately predicting the mean best solution found. For weak selection and
large problem size the difference equations describing the dynamics can be
expressed analytically and we find that the effects of noise due to the finite
size of each training batch can be removed by increasing the population size
appropriately. If this population resizing is used, one can deduce the most
computationally efficient size of training batch each generation. For
independent patterns this choice also gives the minimum total number of
training patterns used. Although using independent patterns is a very
inefficient use of training patterns in general, this work may also prove
useful for determining the optimum batch size in the case where patterns are
recycled.Comment: 28 pages, 4 Postscript figures. Latex using IOP macros ioplppt and
iopl12 which are included. To appear in Journal of Physics A. Also available
at ftp://ftp.cs.man.ac.uk/pub/ai/jls/GAlearn.ps.gz and
http://www.cs.man.ac.uk/~jl
Predicting expected TCP throughput using genetic algorithm
Predicting the expected throughput of TCP is important for several aspects such as e.g. determining handover criteria for future multihomed mobile nodes or determining the expected throughput of a given MPTCP subflow for load-balancing reasons. However, this is challenging due to time varying behavior of the underlying network characteristics. In this paper, we present a genetic-algorithm-based prediction model for estimating TCP throughput values. Our approach tries to find the best matching combination of mathematical functions that approximate a given time series that accounts for the TCP throughput samples using genetic algorithm. Based on collected historical datapoints about measured TCP throughput samples, our algorithm estimates expected throughput over time. We evaluate the quality of the prediction using different selection and diversity strategies for creating new chromosomes. Also, we explore the use of different fitness functions in order to evaluate the goodness of a chromosome. The goal is to show how different tuning on the genetic algorithm may have an impact on the prediction. Using extensive simulations over several TCP throughput traces, we find that the genetic algorithm successfully finds reasonable matching mathematical functions that allow to describe the TCP sampled throughput values with good fidelity. We also explore the effectiveness of predicting time series throughput samples for a given prediction horizon and estimate the prediction error and confidence.Peer ReviewedPostprint (author's final draft
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