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What Genetic Programming ISN'T:What Genetic Programming ISN'T:Engineering a breed of purple carrots.Engineering a breed of purple carrots.Analyzing the human genomeAnalyzing the human genomeA way to create smarter humans.A way to create smarter humans.

What Genetic Programming IS:What Genetic Programming IS:A way to create smarter computers.A way to create smarter computers.Fun.Fun.

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A big Q in A.I.A big Q in A.I.

"How can computers learn to solve "How can computers learn to solve problems without being explicitly problems without being explicitly programmed?" programmed?"

Arthur Samuel (1959)Arthur Samuel (1959)0 01

0

1 011

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The GP Guide to EvolutionThe GP Guide to Evolution

Charles Darwin

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Charles Darwin Charles Darwin

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Gregor MendelGregor Mendel

“The Father of Genetics”

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““The Code is Alive”The Code is Alive”

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Basic Steps of GPBasic Steps of GP

1.1. Populate Generation 0 with random Populate Generation 0 with random computer programs.computer programs.

1.1. Evaluate how “fit” each program is.Evaluate how “fit” each program is.

2.2. Is the “best-so-far” program “fit Is the “best-so-far” program “fit enough”?enough”?

3.3. Use the “fitness” values to determine Use the “fitness” values to determine which programs will produce offspring, which programs will produce offspring, to create the Next Generation.to create the Next Generation.

2.2. Output the “best-so-far” program.Output the “best-so-far” program.

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PreparationPreparation

Program IngredientsProgram Ingredients(math? “rt 90”? “ifelse”? “fd 1.0”?)(math? “rt 90”? “ifelse”? “fd 1.0”?)

Fitness Measure Fitness Measure How good (attractive) is a program How good (attractive) is a program

(creature)?(creature)?

Parameters Parameters (e.g. pop. size, mutation probability, etc.)(e.g. pop. size, mutation probability, etc.)

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Example: Symbolic RegressionExample: Symbolic Regression

Given: Some points

Find: f(x) = x2 + x + 1

Ingredients {x, random constants {x, random constants between -5.0 and 5.0}between -5.0 and 5.0}{+, -, *, {+, -, *, (protected division)(protected division)}}

A “program” is a math function.

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Into the DNA Forest…Into the DNA Forest…

Generation 0

A program is just a tree.

Pop. Size = 4

(x + 1) – 0 1 + (x * x) 2 + 0 x * (-1 – (-2))

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Fitness MeasureFitness Measure

.67 1.00 1.70 2.67

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The Birds and the Bytes…The Birds and the Bytes…

3 Fundamental Genetic Operations3 Fundamental Genetic OperationsCloning (Asexual Reproduction)Cloning (Asexual Reproduction)MutationMutationCrossover (Recombination)Crossover (Recombination)

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CloningCloning

Fitness = .67

Generation 0 Generation 1

COPY

Fitness = .67

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MutationMutation

Fitness = 1.70

Generation 0 Generation 1

Mutate

Fitness = ?

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CrossoverCrossover

Crossover

Generation 0 Generation 1

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Gen 0Gen 0 Gen 1Gen 1

Copy

MutateCrossover

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On to the turtles...On to the turtles...

Genetic Programming in NetLogo...