Equivalent birational embedding IV: reduced varieties

Abstract

Two reduced projective schemes are said to be Cremona equivalent if there is a Cremona map that maps one in the other. In this paper I revise some of the known results about Cremona equivalence and extend the main result of [MP09] to reduced schemes. This allows to prove a very general contractibility result for union of rational subvarieties.

to appear in the special volume on "Rationality problems" of the Rend. Circ. Mat. Palermo