Evolutionary systems & genetic algorithms

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Current revision (22:11, 9 September 2013) (view source)
(Further Evolutionary Art Development by Karl Sims: Added a link to NEvAr)
 
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* A way to select genotypes based on their scores and then modify or recombine them for expression
* A way to select genotypes based on their scores and then modify or recombine them for expression
* A way to express genotypes to create phenotypes
* A way to express genotypes to create phenotypes
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* A way to assign each genotype a score based on an evaluation of the corresponding phenotype
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* A way to assign each genotype a fitness score based on an evaluation of the corresponding phenotype
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== Methods for Providing Fitness Scores ==
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In various industrial applications fitness can be automatically evaluated using objective measures.  For example, competing genetically based investment tools can be evaluated simply by comparing their rate of return on investment.  Automated fitness scores in the arts, sometime called Computational Aesthetic Evaluation, is an exceedingly difficult unsolved problem.  A viable alternative is for the artist himself to score phenotypical expressions creating an Interactive Evolutionary System.  However, with the artist "in the loop" the population size and the number of generations are both severely limited.
== Types of Genetic Representations ==
== Types of Genetic Representations ==
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There are at least 4 types of genotype representation that can be differentiated based on the mechanisms they use.  Each has a different complexification capacity, i.e. some representations lead to more complexity than others.   
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Another significant challenge for evolutionary artists is the design of the genotype.  There are at least 4 types of genotype representation that can be differentiated based on the mechanisms they use.  Each has a different complexification capacity, i.e. some representations lead to more complexity than others.   
* '''''Fixed Parametric''''' - A genotype that uses a fixed number of parameters that map into phenotypical characteristics in a one-to-one manner. The complexification capacity of this system is highly constrained.  
* '''''Fixed Parametric''''' - A genotype that uses a fixed number of parameters that map into phenotypical characteristics in a one-to-one manner. The complexification capacity of this system is highly constrained.  
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In addition the rate of mutation may be a genetic variable. This provides some relief in deciding what the mutation rate should be. The optimal mutation rate will then evolve. It's even possible that the mutation rate will self-adjust over time. Typically at the start the mutation rate should be higher (randomization) than it is later (when fine tuning). It's worth noting that some cases have been found in nature where the mutation rate increases in response to increased environmental pressure. This too could be simulated by calculating the mutation rate as a function of both genetics and environmental pressure.
In addition the rate of mutation may be a genetic variable. This provides some relief in deciding what the mutation rate should be. The optimal mutation rate will then evolve. It's even possible that the mutation rate will self-adjust over time. Typically at the start the mutation rate should be higher (randomization) than it is later (when fine tuning). It's worth noting that some cases have been found in nature where the mutation rate increases in response to increased environmental pressure. This too could be simulated by calculating the mutation rate as a function of both genetics and environmental pressure.
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  010<font color="red">0</font>      XOR      011<font color="red">1</font>
  010<font color="red">0</font>      XOR      011<font color="red">1</font>
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== Example of Classic Genetic Programming for Problem Solving - Lawrence Fogel ==
 
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Fogel is a graduate of NYU (B.S.E.E. 1948) and began the field of genetic programming in the mid-1960's. Genetic programming was used as a way to optimize solutions to problems with no exact or analytic solution.
 
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<span style="font-size:larger;">The Traveling Salesman problem</span>
 
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The goal of this classic optimization problem is to craft a path visiting each location once and only once in the shortest distance possible.
 
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<span style="font-size:larger">Image synthesis</span>
<span style="font-size:larger">Image synthesis</span>
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Karl Sims uses an old idea to create new art. In this SigGraph paper he describes how mathematical expressions can be treated as an assembly of genes. Ashley Mills offers a simplified explaination of this method here.
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Karl Sims uses an old idea to create new art. In this SigGraph paper he describes how mathematical expressions can be treated as an assembly of genes. His paper can be found [http://www.karlsims.com/papers/siggraph91.html here.]
Basically the expression is parsed into a tree structure, and then subjected to mutations, or a form of crossover by substituting entire branches of the tree. An equivalent implementation can be done by using text oriented regular expression processing techniques. The resulting phenotype is an image computed pixel by pixel by evaluating each expression substituting the specific (x,y) coordinate.
Basically the expression is parsed into a tree structure, and then subjected to mutations, or a form of crossover by substituting entire branches of the tree. An equivalent implementation can be done by using text oriented regular expression processing techniques. The resulting phenotype is an image computed pixel by pixel by evaluating each expression substituting the specific (x,y) coordinate.
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* Image processing or video processing can be done by calculating pixel values as a function of (x,y,i,t) where i is the value of the image channel and t is time.
* Image processing or video processing can be done by calculating pixel values as a function of (x,y,i,t) where i is the value of the image channel and t is time.
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Worth noting in this realm is the NEvAr system that automates the fitness function by using (more or less) the ratio of two complexity measures, compressibility via JPEG versus compressibility via fractal methods. A paper documenting NEvAr can be found [https://estudogeral.sib.uc.pt/bitstream/10316/7641/1/obra.pdf here.]
== Interactive Genetic Art Installation ==
== Interactive Genetic Art Installation ==

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