Dakota Reference Manual  Version 6.12
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replacement_type


Select a replacement type for SCOLIB evolutionary algorithm (coliny_ea)

Specification

Alias: none

Argument(s): none

Default: elitist=1

Child Keywords:

Required/Optional Description of Group Dakota Keyword Dakota Keyword Description
Required
(Choose One)
Replacement Type (Group 1) random Create new population randomly
chc Create new population using replacement
elitist Use the best designs to form a new population
Optional new_solutions_generated Replace population with individuals chosen from population

Description

The replacement_type controls how current populations and newly generated individuals are combined to create a new population. Each of the replacement_type selections accepts an associated integer value, which is specified by the replacement_size:

The random setting creates a new population using (a) replacement_size randomly selected individuals from the current population, and (b) population_size - replacement_size individuals randomly selected from among the newly generated individuals (the number of which is optionally specified using new_solutions_generated) that are created for each generation (using the selection, crossover, and mutation procedures).

The chc setting creates a new population using (a) the replacement_size best individuals from the combination of the current population and the newly generated individuals, and (b) population_size - replacement_size individuals randomly selected from among the remaining individuals in this combined pool. The chc setting is the preferred selection for many engineering problems.

The elitist (default) setting creates a new population using (a) the replacement_size best individuals from the current population, (b) and population_size - replacement_size individuals randomly selected from the newly generated individuals. It is possible in this case to lose a good solution from the newly generated individuals if it is not randomly selected for replacement; however, the default new_solutions_generated value is set such that the entire set of newly generated individuals will be selected for replacement.

Note that new_solutions_generated is not recognized by Dakota as a valid keyword unless replacement_type has been specified.