Source: wikibot/birational-invariant
= Birational invariant
{wiki=Birational_invariant}
In algebraic geometry, a **birational invariant** is a property of a variety (or more generally, an algebraic scheme) that remains unchanged under birational equivalence. Two varieties \\( X \\) and \\( Y \\) are said to be birationally equivalent if there exist rational maps from \\( X \\) to \\( Y \\) and from \\( Y \\) to \\( X \\) that are inverses of each other on a dense open subset of each variety.