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A. Pascal
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Birational correspondences and codimension where not an isomorphism

A question inspired by Is the Euler characteristic a birational invariant:

As remarked in Mike Roth's answer to the above linked question, if $X$ and $Y$ are smooth projective varieties in characteristic zero that are birational, then there is a smooth $Z$ with morphisms $p: Z \rightarrow X$ and $q: Z \rightarrow Y$ that are both birational isomorphisms.

Question: Is it possible to arrange for at least one of $p$ and $q$ that the locus in $Z$ where the morphism fails to be an isomorphism is of codimension at least $2$?

Here it might be useful to assume that ${\rm dim}X={\dim Y} \geq 3$.

A. Pascal
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