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Notes on the Distinction of Gaussian and Cauchy Mutations. Speaker : Kuo-Torng, Lan. Ph. D. Takming Univ. of Science and Technology. I. Introduction II. Analyses of Two Mutations III. Simulation Results IV. Conclusions. I. Introduction. Rank or Roulette-wheel selection?
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Notes on the Distinction of Gaussian and Cauchy Mutations Speaker:Kuo-Torng, Lan. Ph. D. Takming Univ. of Science and Technology
I. Introduction II. Analyses of Two Mutations III. Simulation Results IV. Conclusions
I. Introduction • Rank or Roulette-wheel selection? • Gaussian or Cauchy mutation? • Population size? Mutation step size? … • escaping local optima & converging to the global optimum
I. Introduction Individuals: walk randomly Population: go toward the local(global) optimum
II. Analyses of Two Mutations • Assume the dimension of the individual is 1. • Assume the mutation step size is • The mutation is
II. Analyses of Two Mutations • And X is a random variable with the Gaussian distribution. Its pdf is • And X is a random variable with the Cauchy distribution. Its pdf is
II. Analyses of Two Mutations • Condition 1: Local Escape on Valley landscape
II. Analyses of Two Mutations • Condition 1: Local Escape on Valley landscape For GMO: For CMO:
II. Analyses of Two Mutations • Condition 2: Local Convergence on hill landscape
II. Analyses of Two Mutations • Condition 2: Local Convergence on hill landscape For GMO: For CMO:
III. Simulation Results • Benchmark function 1: Ackey function • Benchmark function 2: modified Schaffer function • DC motor control(2005) • 2D fractal pattern Design(2006) • 3D fractal pattern Design(2008)
III. Simulation Results • Benchmark function 1: Ackey function
III. Simulation Results • Benchmark function 1: Ackey function
III. Simulation Results • Benchmark function 1: Ackey function - by Gaussian mutation
III. Simulation Results • Benchmark function 1: Ackey function - by Cauchy mutation
III. Simulation Results • Benchmark function 2: modified Schaffer function
III. Simulation Results • Benchmark function 2: modified Schaffer function
III. Simulation Results • Benchmark function 2: modified Schaffer function
III. Simulation Results • Benchmark function 2: modified Schaffer function
III. Simulation Results • DC motor control: (K. T. Lan,“Design a rule-based controller for DC servo-motor Control byevolutionary computation,” TAAI 2005, in Chinese.)
III. Simulation Results • DC motor control: (K. T. Lan,“Design a rule-based controller ...) The chromosome (i.e. control table)
III. Simulation Results • DC motor control: (K. T. Lan,“Design a rule-based controller …,” )
III. Simulation Results • 2D fractal pattern Design: (K. T. Lan,et al.,“Design a 2D fractal pattern by using the evolutionary computation,” TAAI 2006, in Chinese.)
III. Simulation Results • 2D fractal pattern Design: (K. T. Lan,et al.,“Design a ...) The chromosome (i.e. 2D pattern)
III. Simulation Results • 2D fractal pattern Design: (K. T. Lan,et al.,“Design a ...)
III. Simulation Results • 3D fractal pattern Design: (K. T. Lan,et al.,“The problems for design a 3D fractal pattern by using the evolutionary computation,” TAAI 2008, in Chinese.) The Cauchy mutation is predominant to Gaussian.
III. Simulation Results • 3D fractal pattern Design: (K. T. Lan,et al.,“The problems for design a 3D fractal pattern by using the evolutionary computation,” TAAI 2008, in Chinese.) Searching space: 10x10x10 No. of Reef: 60 Near optimal design: FD= 2.3843
III. Simulation Results • 3D fractal pattern Design: (K. T. Lan,et al.,“The problems for design a 3D fractal pattern by using the evolutionary computation,” TAAI 2008, in Chinese.) Searching space: 12x12x12 No. of Reef: 94 Near optimal design: FD=2.4055
IV. Conclusions • A larger mutation step size can lead population to escape local optima and tend towards the global optimum • A smaller mutation step size can finely tune the population • Cauchy mutation possesses more power in escaping local optima
IV. Conclusions • For local convergence, the Cauchy technique is nearly equal to the Gaussian after evolving more generations. • Therefore, Cauchy mutation is suggested to avoid the dilemma problem and achieve the acceptable performance for evolutionary computation. Thanks for your kindly attention.