L2-cohomology and intersection homology of certain algebraic varieties with isolated singularities.
La condition “ constant” est une condition numérique d’équisingularité introduite par B. Teissier. Celui-ci a démontré dans (Astérisque, 7 & 8 (1973) II. Théorème 3.9) que cette condition implique les conditions de Whitney, nous montrons ici la réciproque.
We study liftings or deformations of -modules ( is the ring of differential operators from EGA IV) from positive characteristic to characteristic zero using ideas of Matzat and Berthelot’s theory of arithmetic -modules. We pay special attention to the growth of the differential Galois group of the liftings. We also apply formal deformation theory (following Schlessinger and Mazur) to analyze the space of all liftings of a given -module in positive characteristic. At the end we compare the problems...
Let denote the set of log canonical thresholds of pairs , with a nonsingular variety of dimension , and a nonempty closed subscheme of . Using non-standard methods, we show that every limit of a decreasing sequence in lies in , proving in this setting a conjecture of Kollár. We also show that is closed in ; in particular, every limit of log canonical thresholds on smooth varieties of fixed dimension is a rational number. As a consequence of this property, we see that in order to check...
We show that every n-dimensional smooth algebraic variety X can be covered by Zariski open subsets which are isomorphic to closed smooth hypersurfaces in . As an application we show that forevery (pure) n-1-dimensional ℂ-uniruled variety there is a generically-finite (even quasi-finite) polynomial mapping such that . This gives (together with [3]) a full characterization of irreducible components of the set for generically-finite polynomial mappings .
We propose a new method for defining a notion of support for objects in any compactly generated triangulated category admitting small coproducts. This approach is based on a construction of local cohomology functors on triangulated categories, with respect to a central ring of operators. Special cases are, for example, the theory for commutative noetherian rings due to Foxby and Neeman, the theory of Avramov and Buchweitz for complete intersection local rings, and varieties for representations of...
Let be an ideal of a commutative Noetherian ring . It is shown that the -modules are -cofinite for all finitely generated -modules and all if and only if the -modules and are -cofinite for all finitely generated -modules , and all integers .
Using a recently introduced correspondence of Emerton-Kisin we give a description of Lyubeznik’s local cohomology invariants in terms of local étale cohomology with coefficients.