Annals of Mathematics, Second Series, Vol. 155, No. 2 (Mar., 2002), pp. 491-551 (61 pages) An important breakthrough in understanding the geometry of Schubert varieties was the introduction of the ...

For a variety X of positive characteristic and a nonnegative integer e, we define its e-th F blowup to be the universal flattening of the e-iterated Frobenius of X. Thus we have the sequence (a set ...