Canonical Big Cohen-Macaulay Algebras with Applications to Singularities
نویسنده
چکیده
A canonical construction of a balanced big Cohen-Macaulay algebra for a domain of finite type over C is obtained by taking ultraproducts of absolute integral closures in positive characteristic. Among the applications are a new tight closure characterization of rational singularities in characteristic zero, and a necessary condition for Q-Gorenstein logterminal singularities. In particular, it is shown that log-terminal singularities descend under pure homomorphisms. Inventiones mathematicae manuscript No. (will be inserted by the editor) Canonical Big Cohen-Macaulay Algebras with Applications to Singularities
منابع مشابه
Canonical Big Cohen-macaulay Algebras and Rational Singularities
We give a canonical construction of a balanced big Cohen-Macaulay algebra for a domain of finite type over C by taking ultraproducts of absolute integral closures in positive characteristic. This yields a new tight closure characterization of rational singularities in characteristic zero.
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