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The ‘Representative’pattern is applicable when it is desirable to eliminate redundancy in the search process:• It is often the case that some function f of interest in optimization gives a many-to-one mapping, ie it induces equivalence classes over the image of f. If f is a fitness function, this can lead to plateaus in the fitness landscape.

• It may be that the elimination of redundancy allows search to be performed in a smaller (‘quotient’) space that can be searched using methods (possibly even exact techniques) not applicable to the original space.• In the case of GP-trees, syntactically inequivalent but semantically equivalent representations (eg x+ x, 2∗ x) can lead to a lack of gradient in genotype-to-phenotype mappings, whichmaymake the space of programs harder to search effectively.