public Builder<G, C> populationSize(final int size) {
			_evolutionParams.populationSize(size);
			return this;
		}
The number of individuals which form the population. <i>Default
values is set to {@code 50}.</i>

@param size the number of individuals of a population
@return {@code this} builder, for command chaining
@throws java.lang.IllegalArgumentException if {@code size < 1}
jenetics/src/main/java/io/jenetics/engine/Engine.java