Functorial affinization of Nash's manifold
Abstract
Let M be a singular irreducible complex manifold of dimension n. There are Q divisors D[-1], D[0], D[1],...,D[n+1] on Nash's manifold U -> M such that D[n+1] is relatively ample on bounded sets, D[n] is relatively eventually basepoint free on bounded sets, and D[-1] is canonical with the same relative plurigenera as a resolution of M. The divisor D=D[n] is the supremum of divisors (1/i)Di. An arc g containing one singular point of M lifts to U if and only if the generating number of oplusi Og(Di) is finite. When it is finite it equals 1+(KU-K) .g where OU(K) is the pullback mod torsion of Lambdan OmegaM. If C is a complete curve in U then (-1/(n+1))KU .C=D1 .C + Dn+2 .C + D(n+2)2 .C +..... When there are infinitely many nonzero terms the sum should be taken formally or p-adically for a prime divisor p of n+2. There are finitely many nonzero terms if and only if C. D=0. The natural holomorphic map U -> M factorizes through the contracting map U -> Y0. If M is bounded, the Grauert-Riemenschneider sheaf of M is Hom(OM(D(n+2)i - 1), OM(D(n+2)i)) for large i. If M is projective, singular foliations on M such that K+(n+1)H is a finitely-generated divisor of Iitaka dimension one are completely resolvable, where K is the canonical divisor of the foliation and H is a hyperplane. There are some precise open questions in the article. According to a question of [7] it is not known whether Y0 has canonical singularities.
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