智能控制智能控制智能控制 (56).pdf

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1、Basic Mechanism of GABasic Concept Individuals and populations An individual usually refers to a solution of the problem by simulating a biological individual.A population is a group composed of several individuals that simulates a biological population.Basic Concept Fitness and Fitness function Fit

2、ness refers to the degree of adaptation of individual organisms tothe environment,and a measure designed to characterize the prosand cons of the individual objects.Fitness function is a correspondence between all individuals in the problem and their fitness.Basic Concept Chromosomes and genes The ch

3、romosome is the coded representation of the individual in the form of a certain string.The characters in the string are also called genes.e.g.IndividualChromosomes10(1,3,7)1010001 101 111Genetic ManipulationAlso known as genetic operator,it is about the operation of chromosome.SelectionThere are thr

4、ee types of genetic operations in genetic algorithms:Crossover MutationSelectionFor a population S of size N,according to the probability P()of each chromosome X.N chromosomes are randomly selected from S in N times and copied.The calculation formula of probability P()i iNijj 1f xP xf xOne-point Cro

5、ssover One position in the chromosomes is randomly chosen Child 1 is head of chromosome of parent 1 with tail of chromosome of parent 2 Child 2 is head of 2 with tail of 1Parents:10100011100011010010Offspring:10100100100011001110Randomly chosen position Randomly two positions in the chromosomes are

6、chosen Avoids that genes at the head and genes at the tail of a chromosome are always split when recombinedTwo-point CrossoverParents:1 0 10 0 0 1 1 1 00 0 1 1 0 1 0 0 1 0Offspring:1 0 10 0 1 00 1 00 0 1 1 0 0 1 1 1 0Randomly chosen positionsUniform Crossover A random mask is generated The mask dete

7、rmines which bits are copied from one parent and which from the other parent Bit density in mask determines how much material is taken from the other parent(takeover parameter)Mask:0110011000 (Randomly generated)Parents:10100011100011010010Offspring:00110010101010010110MutationMutation is to change a gene on a certain position(s)of the chromosome.For example:=11001101Change the 0 in the third position to 1=111001101SummaryBasic ConceptIndividuals and populationsFitness and Fitness functionChromosomes and genesGenetic manipulationSelection-reproductionCrossoverMutation