👉 In mathematics, a nonvariety is a type of object that is not a subset of another type. Nonvarieties are important in algebraic geometry and topology because they provide examples of objects that are not in the category of sets but are also not subsets of any other set. For example, a nonvariety could be an affine variety in projective space P^n, which is defined as a subspace of P^n consisting of all points whose coordinates satisfy some linear equation. In topology,