Lemma 10.70.10. Let R be a domain, I \subset R an ideal, and a \in I a nonzero element. Then the affine blowup algebra R[\frac{I}{a}] is a domain.
Proof. Suppose x/a^ n, y/a^ m with x \in I^ n, y \in I^ m are elements of R[\frac{I}{a}] whose product is zero. Then a^ N x y = 0 in R. Since R is a domain we conclude that either x = 0 or y = 0. \square
Comments (0)
There are also: