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Unformatted text preview: tems Issues in performance evaluation According to what criteria should GAs be evaluated? What does it mean for a GA to do well or poorly? Under what conditions is a GA an appropriate solution strategy for a problem? Theoretical Foundation Holland’s observations An adaptive system must persistently identify, test, and incorporate structural properties hypothesized to give better performance in some environment Adaptation is impossible in a sufficiently random environment Theoretical Foundation Holland’s intuition A GA is capable of modeling the necessary tasks in an adaptive system It does so through a combination of explicit computation and implicit estimation of state combined with incremental change of state in directions motivated by these calculations Theoretical Foundation Holland’s assertion The ‘identify and test’ requirement is satisfied by the calculation of the fitnesses of various schemas The ‘incorporate’ requirement is satisfied by implication of the Schema Theorem Theoretical Foundation How does a GA identify and test properties? A schema is the formalization of a property A GA explicitly calculates fitnesses of individuals and thereby schemas in the population It implicitly estimates fitnesses of hypothetical individuals sharing known schemas In this way it efficiently manages information regarding the entire search space Theoretical Foundation How does a GA incorporate observed good properties into the population? Implication of...
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This note was uploaded on 04/05/2010 for the course CS 723 taught by Professor Sc during the Spring '10 term at Jaypee University IT.
- Spring '10