Source: wikibot/rasiowa-sikorski-lemma
= Rasiowa–Sikorski lemma
{wiki=Rasiowa–Sikorski_lemma}
The Rasiowa–Sikorski lemma is a result in the field of mathematical logic, particularly in set theory and model theory. It provides a criterion for determining whether a certain kind of subset exists in a model of set theory. The lemma is named after the mathematicians Helena Rasiowa and Andrzej Sikorski, who contributed to the field of logic in the mid-20th century.