Editing Tournament selection (section)

{{Short description|Selection method in genetic algorithms}}
'''Tournament selection''' is a method of selecting an individual from a population of individuals in a [[evolutionary algorithm]].<ref>{{cite journal |last1=ZHANG |first1=Byoung-Tak |last2=KIM |first2=Jung-Jib |title=Comparison of Selection Methods for Evolutionary Optimization |journal=Evolutionary Optimization |date=2000 |url=https://citeseerx.ist.psu.edu/document?doi=d356a3e21bb51d0a1258d661066e99fa8fe0ed05}}</ref><ref name=miller-goldberg>{{cite journal|last1=Miller|first1=Brad|last2=Goldberg|first2=David|title=Genetic Algorithms, Tournament Selection, and the Effects of Noise|journal=Complex Systems|date=1995|volume=9|pages=193–212|s2cid=6491320|url=https://pdfs.semanticscholar.org/df6e/e94e2cf14c38e9cff4d2446a50db0aedd4ca.pdf|archive-url=https://web.archive.org/web/20190831154511/https://pdfs.semanticscholar.org/df6e/e94e2cf14c38e9cff4d2446a50db0aedd4ca.pdf|url-status=dead|archive-date=2019-08-31}}</ref> Tournament selection involves running several "tournaments" among a few individuals (or "[[chromosome (genetic algorithm)|chromosome]]s") chosen at random from the population.  The winner of each tournament (the one with the best fitness) is selected for [[Crossover (genetic algorithm)|crossover]].  
''[[Selection pressure]]'' is then a probabilistic measure of a chromosome's likelihood of participation in the tournament based on the participant selection pool size, is easily adjusted by changing the tournament size. The reason is that if the tournament size is larger, weak individuals have a smaller chance to be selected, because, if a weak individual is selected to be in a tournament, there is a higher probability that a stronger individual is also in that tournament.