applications of genetic algorithms tjhsst computer systems lab 2008-2009 by mary linnell
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What is a Genetic Algorithm?
Evolutionary algorithm Population consisting of
individuals Needs a function to evaluate
each individual Least fit individuals killed off Best fit individuals breed with
rest of population
http://www.lifeinthefastlane.ca/wp-content/uploads/ 2007/10/king_penguin_breeding_1sfw.jpg
A population of penguins
Genetic Algorithm Applications
N Queens Problem Optimizing of Traveling
Salesman Problem Othello Any problem with a population
able to be characterized by a function
http://en.wikipedia.org/wiki/N_queens_problem
http://images.boardgamegeek.com/images/pic158681_md.jpg
Purpose and Goals
Find minimum point of a three-dimensional graph
Testing every point would involve too many computations
Use genetic algorithms to simplify this problem
Purpose and Goals
Vary the population size to see what is “best” If too small
Population not representative of search space Population will converge to a local minimum Too many random mutations to find true
solution If too large
Long run times Large amount of computer space and memory
Scope of Study and Project
C Genetic algorithm Analytical display of results
OpenGL 3D graphics Visual display of results
Approximate answer should closely match exact answer
Procedure and Methods
Wire-mesh display of graph with mouse controls
Lots of local minimums N randomly-generated
yellow points, where N is the number in the population
z=−cos x∗8.0 cos y∗8.0∗1−x ∗1− y
5.0
Controls
Reset: re-initializes all values, increments seed Step: steps through the genetic algorithm One iteration: runs 5 steps (a full cycle) Single Trial: runs a fixed number of iterations Multiple Trials: runs a fixed number of single trials
Procedure and Methods
Cycle of the genetic algorithm steps: 25% of the population population selected based on
the fitness function Delete selected points New points are bred based on best point Random mutation New points become part of the population
Results of Multiple Trials
True z-value for graph used: -0.84411 Population size of 8
Average result: -0.52009 Difference from true minimum: 0.32403
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