A genetic algorithm with disruptive selection

Genetic algorithms are a class of adaptive search techniques based on the principles of population genetics. The metaphor underlying genetic algorithms is that of natural evolution. Applying the “survival-of-the-fittest” principle, traditional genetic algorithms allocate more trials to above-average schemata. However, increasing the sampling rate of schemata that are above average does not guarantee convergence to a global optimum; the global optimum could be a relatively isolated peak or located in schemata that have large variance in performance. In this paper we propose a novel selection method, disruptive selection. This method adopts a nonmonotonic fitness function that is quite different from traditional monotonic fitness functions. Unlike traditional genetic algorithms, this method favors both superior and inferior individuals. Experimental results show that GAs using the proposed method easily find the optimal solution of a function that is hard for traditional GAs to optimize. We also present convergence analysis to estimate the occurrence ratio of the optima of a deceptive function after a certain number of generations of a genetic algorithm. Experimental results show that GAs using disruptive selection in some occasions find the optima more quickly and reliably than GAs using directional selection. These results suggest that disruptive selection can be useful in solving problems that have large variance within schemata and problems that are GA-deceptive     

Genetic diversity as an objective in multi-objective evolutionary algorithms

A key feature of an efficient and reliable multi-objective evolutionary algorithm is the ability to maintain genetic diversity within a population of solutions. In this paper, we present a new diversity-preserving mechanism, the Genetic Diversity Evaluation Method (GeDEM), which considers a distance-based measure of genetic diversity as a real objective in fitness assignment. This provides a dual selection pressure towards the exploitation of current non-dominated solutions and the exploration of the search space. We also introduce a new multi-objective evolutionary algorithm, the Genetic Diversity Evolutionary Algorithm (GDEA), strictly designed around GeDEM and then we compare it with other state-of-the-art algorithms on a well-established suite of test problems. Experimental results clearly indicate that the performance of GDEA is top-level.     

Multi-objective genetic local search algorithm using Kohonen’s neural map

Genetic Algorithms (GAs) are population based global search methods that can escape from local optima traps and find the global optima regions. However, near the optimum set their intensification process is often inaccurate. This is because the search strategy of GAs is completely probabilistic. With a random search near the optimum sets, there is a small probability to improve current solution. Another drawback of the GAs is genetic drift. The GAs search process is a black box process and no one knows that which region is being searched by the algorithm and it is possible that GAs search only a small region in the feasible space. On the other hand, GAs usually do not use the existing information about the optimality regions in past iterations.In this paper, a new method called SOM-Based Multi-Objective GA (SBMOGA) is proposed to improve the genetic diversity. In SBMOGA, a grid of neurons use the concept of learning rule of Self-Organizing Map (SOM) supporting by Variable Neighborhood Search (VNS) learn from genetic algorithm improving both local and global search. SOM is a neural network which is capable of learning and can improve the efficiency of data processing algorithms. The VNS algorithm is developed to enhance the local search efficiency in the Evolutionary Algorithms (EAs). The SOM uses a multi-objective learning rule based-on Pareto dominance to train its neurons. The neurons gradually move toward better fitness areas in some trajectories in feasible space. The knowledge of optimum front in past generations is saved in form of trajectories. The final state of the neurons determines a set of new solutions that can be regarded as the probability density distribution function of the high fitness areas in the multi-objective space. The new set of solutions potentially can improve the GAs overall efficiency. In the last section of this paper, the applicability of the proposed algorithm is examined in developing optimal policies for a real world multi-objective multi-reservoir system which is a non-linear, non-convex, multi-objective optimization problem.     

一种新的遗传模拟退火算法的软硬件划分方法

针对嵌入式系统软硬件划分问题,在分析遗传算法和模拟退火算法的主要优缺点的基础上,提出了一种新的小生境技术改进的遗传模拟退火算法（NGSA）,在遗传算法中融入模拟退火思想,同时引入小生境技术,保持群体的多样性;并采用Metropolis 法则形成新群体,改善群体的质量。实验结果证明该算法具有很强的爬山能力和全局搜索能力,与遗传算法（GA）和模拟退火算法（SA）相比适应度明显提高。     

Why DGAs work well on GA-hard functions?

What makes a problem easy or hard for a genetic algorithm (GA)? Much previous work has studied this question by applying Walsh analysis.⁴⁾ In this paper, we demonstrate a function that is GA-hard by analyzing the Walsh coefficients of this function’s Walsh decomposition. Then, we construct five functions with differing degrees of difficulty for genetic algorithms. Some are GA-easy and some are GA-hard. In a previous paper,²⁹⁾ wh have proposed a novel selection method,disruptive selection. This method devotes more trials to both better solutions and worse solutions than it does to moderate solutions, whereas the conventional method allocates its attention according to the performance of each solution. Experimental results show that DGAs (GAs using disruptive selection) perform very well on both GA-easy and GA-hard functions. Finally, we discuss why DGAs outperform conventional GAs.     

演化信息协助的动态协同随机漂移粒子群优化算法

为了改善随机漂移粒子群算法的群体多样性,通过演化信息的协助,提出动态协同随机漂移粒子群优化（CRDPSO）算法。利用上下文粒子的向量信息,粒子之间的动态协作增加了种群多样性,这有助于提高群体的搜索能力,并使整个群体协同搜索全局最优值。同时在演化过程中的每次迭代,利用二维空间分割树结构来存储算法中的估计解的位置和适应度值,从而实现快速适应度函数逼近。由于适应度函数逼近增强了变异策略,因此变异是自适应且无参数的。通过典型测试函数将CRDPSO算法和差分进化算法（DE）、协方差矩阵适应进化策略算法（CMA-ES）、非重复访问遗传算法（cNrGA）以及三种改进的量子行为粒子群算法（QPSO）进行比较。实验结果表明,不管是对于单峰还是多峰测试函数,CRDPSO的性能均是最优的,证明了该算法的有效性。     

演化信息协助的动态协同随机漂移粒子群优化算法

为了改善随机漂移粒子群算法的群体多样性，通过演化信息的协助，提出动态协同随机漂移粒子群优化（CRDPSO）算法。利用上下文粒子的向量信息，粒子之间的动态协作增加了种群多样性，这有助于提高群体的搜索能力，并使整个群体协同搜索全局最优值。同时在演化过程中的每次迭代，利用二维空间分割树结构来存储算法中的估计解的位置和适应度值，从而实现快速适应度函数逼近。由于适应度函数逼近增强了变异策略，因此变异是自适应且无参数的。通过典型测试函数将CRDPSO算法和差分进化算法（DE）、协方差矩阵适应进化策略算法（CMA-ES）、非重复访问遗传算法（cNrGA）以及三种改进的量子行为粒子群算法（QPSO）进行比较。实验结果表明，不管是对于单峰还是多峰测试函数，CRDPSO的性能均是最优的，证明了该算法的有效性。     

基于均匀设计的并行变异遗传算法

针对标准遗传算法易陷入局部最优和局部搜索能力差的缺陷,提出一种基于完全均匀设计的并行变异遗传算法(U D-PMGA)。首先用完全均匀设计方法获得多样性良好的初始种群,之后提出两种改进的锦标赛选择机制,一种改进方法取适应度较高的50%个体覆盖整个群体,另一种改进是用适应度较高且各自不同的50%个体覆盖整个群体。把适应度相近且空间距离较远的两个个体作为交叉对象以提高交叉操作的搜索效率。最后用自适应变异比例和自适应变异步长相结合的并行变异搜索策略提高算法的收敛速度和搜索精度。通过测试函数仿真,并与其它算法比较,验证了UD-PMGA算法的有效性与先进性。     

Dynamic and heuristic fuzzy connectives-based crossover operators for controlling the diversity and convergence of real-coded genetic algorithms

Genetic algorithms are adaptive methods which may be used as approximation heuristic for search and optimization problems. Genetic algorithms process a population of search space solutions with three operations: selection, crossover, and mutation. A great problem in the use of genetic algorithms is the premature convergence, a premature stagnation of the search caused by the lack of diversity in the population and a disproportionate relationship between exploitation and exploration. The crossover operator is considered one of the most determinant elements for solving this problem. In this article we present two types of crossover operators based on fuzzy connectives for real-coded genetic algorithms. The first type is designed to keep a suitable sequence between the exploration and the exploitation along the genetic algorithm's run, the dynamic fuzzy connectives-based crossover operators, the second, for generating offspring near to the best parents in order to offer diversity or convergence in a profitable way, the heuristic fuzzy connectives-based crossover operators. We combine both crossover operators for designing dynamic heuristic fuzzy connectives-based crossover operators that show a robust behavior. © 1996 John Wiley & Sons, Inc.     

基于遗传算法的基坑支护协同演化处理模型

分析了基于遗传算法的协同演化优化方法及深基坑支护的特点。提出了用基于遗传算法的协同演化优化方法来求解基坑支护层次性优化问题的模型,并给出了约束处理和目标函数转换的策略。实例表明所提出的策略是可行有效的。     

Coping with nonstationary environments: a genetic algorithm using neutral variation

In nonstationary environments, it is difficult to apply traditional genetic algorithms (GAs) because they use strong selection pressure and lose the diversity of individuals rapidly. We propose a GA with neutral variation that can track environmental changes. The idea of this GA is inspired by Kimura's neutral theory (1983). The scheme of this GA allows neutral characters, which do not directly affect the fitness with respect to environments, thus increasing the diversity of individuals. In order to demonstrate the properties of this GA, we apply it to a permutation problem called the ladder-network, of which the imposed alignment on the output changes regularly. We show that the GA with neutral variation can adapt better to environmental changes than a traditional GA.     

Backward-chaining evolutionary algorithms

Starting from some simple observations on a popular selection method in Evolutionary Algorithms (EAs)—tournament selection—we highlight a previously-unknown source of inefficiency. This leads us to rethink the order in which operations are performed within EAs, and to suggest an algorithm—the EA with efficient macro-selection—that avoids the inefficiencies associated with tournament selection. This algorithm has the same expected behaviour as the standard EA but yields considerable savings in terms of fitness evaluations. Since fitness evaluation typically dominates the resources needed to solve any non-trivial problem, these savings translate into a reduction in computer time. Noting the connection between the algorithm and rule-based systems, we then further modify the order of operations in the EA, effectively turning the evolutionary search into an inference process operating in backward-chaining mode. The resulting backward-chaining EA creates and evaluates individuals recursively, backward from the last generation to the first, using depth-first search and backtracking. It is even more powerful than the EA with efficient macro-selection in that it shares all its benefits, but it also provably finds fitter solutions sooner, i.e., it is a faster algorithm. These algorithms can be applied to any form of population based search, any representation, fitness function, crossover and mutation, provided they use tournament selection. We analyse their behaviour and benefits both theoretically, using Markov chain theory and space/time complexity analysis, and empirically, by performing a variety of experiments with standard and back-ward chaining versions of genetic algorithms and genetic programming.     

一种求解多目标组合优化的遗传局部搜索算法

为改善遗传算法求解多目标组合优化问题的搜索效率,提出一种新的遗传局部搜索算法.算法采取非劣解并行局部搜索策略以及基于分散度的精英选择策略,并采用基于NSGA-Ⅱ的适应度赋值方式和二元赌轮选择操作,以提高算法收敛性,保持群体多样性.实验结果表明,新算法能够产生数量较多分布较广的近似Pareto最优解.     

ProfARIMA: A profit-driven order identification algorithm for ARIMA models in sales forecasting

In forecasting, evolutionary algorithms are often linked to existing forecasting methods to optimize their input parameters. Traditionally, the fitness function of these search heuristics is based on an accuracy measure. In this paper, however, we combine forecasting accuracy with business expertise by defining a flexible and easily interpretable profit function for sales forecasting, which is based on the profit margin of a given product, the volume of its sales and the accuracy of the forecast. ProfARIMA is a new procedure that selects the lags of a Seasonal ARIMA model according to the profit of a model's forecasts by taking advantage of search heuristics. This procedure is tested on both publicly available datasets and a real-life application with datasets of The Coca-Cola Company in order to assess its performance, both in profit and accuracy. Three different evolutionary algorithms were implemented during this testing process, i.e. Genetic Algorithms, Particle Swarm Optimization and Simulated Annealing. The results indicate that ProfARIMA always performs at least equally to the Box–Jenkins methodology and often outperforms this traditional procedure. For The Coca-Cola Company, our new algorithm in combination with Genetic Algorithms even leads to a significantly larger profit for out-of-sample forecasts.     

High performance genetic algorithm based text clustering using parts of speech and outlier elimination

Among the typical clustering methods, the K-means algorithm plays the most important role in clustering because of its simplicity and efficiency. However, it is sensitive to the initial points and easy to fall into local optimum. In order to avoid this kind of flaw, a patented text clustering algorithm Clustering by Genetic Algorithm Model (CGAM) is revealed in this paper. CGAM constructs the fitness function of genetic algorithm (GA) and convergence criterion for K-means algorithm because GA simulates the natural evolutionary process and deals with a larger search space. To tackle the rich semantics of Chinese texts, CGAM creates an innovative selection method of initial centers of GA and accommodates the contribution of characteristics of different parts of speech. Moreover, the impact of outliers is addressed and treated. Its performance is demonstrated by a series of experiments based on both Reuters-21578 and Chinese text corpus. Experimental results show that the CGAM achieves clustering results better than other GA based K-means algorithms and has been successfully applied to national program of business intelligence system in the context of huge set of contents in both Chinese and English.     

遗传算法中的模式及其转换初探

该文讨论了遗传算法中的模式及其转换。将具有低阶、长定义距以及平均适应度高于群体平均适应度的模式转换为低阶、短定义距以及高平均适应度的模式,有利于提高遗传算法的收敛速度。同时,还讨论了模式转换有利于提高遗传算法的可控制性。     

特征选择在隐秘图像检测中的应用

提出一种基于遗传算法和多超球面一类支持向量机的隐秘图像检测方案。为了得到最能反映分类本质的特征从而有效实现分类识别,采用遗传算法进行图像特征选择,将支持向量机的分类效果作为适应度函数值返回,指导遗传算法搜索最优的特征选择方案。实验结果表明,与仅采用支持向量机分类而未进行特征选择的隐秘检测方案相比,该方案提高了隐秘图像检测的识别率。     

基于排序的改进自适应遗传算法

本文提出了一种改进的自适应遗传算法,其遗传算子由个体在种群中的排序位置自适应地决定,其中选择算子还引入了disruptive selection的思想.该算法能避免群体中超级个体的出现,维持了种群的多样性,加快了种群的收敛速度,克服了遗传算法早熟的现象.函数优化的结果验证了该算法的有效性.     

基于（μ＋λ）选择策略的多目标优化分段遗传算法

在多目标优化遗传算法中，将整个种群按目标函数值划分成若干子种群，在各子种群内μ个父代经遗传操作产生λ个后代；然后将各子种群的所有父代和后代个体收集起来进行种群排序适应度共享，选取较好的个体组成下一代种群。相邻的非劣解容易分在同一子种群有利于提高搜索效率；各子种群间的遗传操作可采用并行处理；各子种群的所有
有个体收集起来进行适应度共享有利于维持种群的多样性。最后给出了计算实例。     

Genetic algorithms in computer aided design

Design is a complex engineering activity, in which computers are more and more involved. The design task can often be seen as an optimization problem in which the parameters or the structure describing the best quality design are sought.Genetic algorithms constitute a class of search algorithms especially suited to solving complex optimization problems. In addition to parameter optimization, genetic algorithms are also suggested for solving problems in creative design, such as combining components in a novel, creative way.Genetic algorithms transpose the notions of evolution in Nature to computers and imitate natural evolution. Basically, they find solution(s) to a problem by maintaining a population of possible solutions according to the ‘survival of the fittest’ principle. We present here the main features of genetic algorithms and several ways in which they can solve difficult design problems. We briefly introduce the basic notions of genetic algorithms, namely, representation, genetic operators, fitness evaluation, and selection. We discuss several advanced genetic algorithms that have proved to be efficient in solving difficult design problems. We then give an overview of applications of genetic algorithms to different domains of engineering design.