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Population Sizing as Population Sizing as an Emergent Behavior an Emergent Behavior Jason Cook Jason Cook

Population Sizing as an Emergent Behavior

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Population Sizing as an Emergent Behavior. Jason Cook. Motivation. Ease of use Limit necessary manual tuning Potentially improve performance. Problem Statement. Remove the population size parameter Introduce no new parameters Maintain useful level of accuracy. Solution Method. - PowerPoint PPT Presentation

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Page 1: Population Sizing as an Emergent Behavior

Population Sizing as Population Sizing as an Emergent an Emergent Behavior Behavior Jason CookJason Cook

Page 2: Population Sizing as an Emergent Behavior

MotivationMotivation

Ease of useEase of use Limit necessary manual tuningLimit necessary manual tuning Potentially improve performancePotentially improve performance

Page 3: Population Sizing as an Emergent Behavior

Problem StatementProblem Statement

Remove the population size parameterRemove the population size parameter Introduce no new parametersIntroduce no new parameters Maintain useful level of accuracyMaintain useful level of accuracy

Page 4: Population Sizing as an Emergent Behavior

Solution MethodSolution Method

Set up the population size as an Set up the population size as an emergent behavioremergent behavior

Replace survivor selection with a survival Replace survivor selection with a survival chancechance

SRSRii = ( = (FFii – – FFminmin)) / ( / (FFmaxmax – – FFminmin))

Page 5: Population Sizing as an Emergent Behavior

Experimental SetupExperimental Setup

Compare with a traditional EACompare with a traditional EA Two main test problems: Griewank Function Two main test problems: Griewank Function

and D-TRAP Problemand D-TRAP Problem Survival Method:Survival Method:

Survival Chance Survival Chance or or

N-TournamentN-Tournament Other operators and parameter held constant Other operators and parameter held constant

for both EAsfor both EAs

Page 6: Population Sizing as an Emergent Behavior

Griewank FunctionGriewank Function

NN dimensional minimization problem dimensional minimization problem Many local optimaMany local optima Optimal solution: Optimal solution: xxii = 0 = 0

Page 7: Population Sizing as an Emergent Behavior

D-TRAPD-TRAP

250 4-bit pieces250 4-bit pieces Each piece is worth:Each piece is worth:

3 – 3 – uu if if uu ≤ 3 ≤ 3 44 otherwiseotherwise

Optimal solution: Optimal solution: xxii = 0 = 0

Page 8: Population Sizing as an Emergent Behavior

ResultsResults

Progression of Fitness values of the Griewank Function

0

10

20

30

40

50

60

70

80

90

100

50 1100 2150 3200 4250 5300 6350 7400 8450 9500

Fitness Evaluations

MB

F (

% o

f m

axim

um

fit

nes

s)

EA-OPT Auto-PS-EA

Page 9: Population Sizing as an Emergent Behavior

Results (Continued):Results (Continued):

Changes in Population Size in the Griewank Function

0

100

200

300

400

500

600

50 1100 2150 3200 4250 5300 6350 7400 8450 9500

Fitness Evaluations

Po

pu

lati

on

Siz

e

Page 10: Population Sizing as an Emergent Behavior

Results (Continued):Results (Continued):

Progression of Fitness Values for the D-TRAP problem

0

10

20

30

40

50

60

70

80

90

100

510 1560 2610 3660 4710 5760 6810 7860 8910 9960

Fitness Evaluations

MB

F (

% o

f m

ax

imu

m p

os

sib

le f

itn

es

s)

Fixed Population Size

Dynamic Population Size

Page 11: Population Sizing as an Emergent Behavior

Results (Continued):Results (Continued):

Changes in Population Size during the D-TRAP problem

0

50

100

150

200

250

510 1560 2610 3660 4710 5760 6810 7860 8910 9960

Fitness Evaluations

Po

pu

lati

on

Siz

e

Page 12: Population Sizing as an Emergent Behavior

AnalysisAnalysis

Performs as well or better than a Performs as well or better than a traditional EAtraditional EA

Still affected by the initial population sizeStill affected by the initial population size

Page 13: Population Sizing as an Emergent Behavior

Future WorkFuture Work

More test problemsMore test problems Use a more competitive EA to test Use a more competitive EA to test

againstagainst

Page 14: Population Sizing as an Emergent Behavior

Questions?Questions?