Strict transform of an algebraic subvariety
= Strict transform of an algebraic subvariety
{title2=$\widetilde Y=\overline{\pi^{-1}(Y\setminus Z)}$}
For a <blowup of an algebraic variety> $\pi:\widetilde X\to X$ with centre $Z$, the <strict transform of an algebraic subvariety> of a subvariety $Y$ not contained in $Z$ is the closure of $\pi^{-1}(Y\setminus Z)$. It excludes components supported entirely in the <algebraic exceptional divisor>.