BGG correspondence and Roemer's theorem on an exterior algebra

Sheaf Cohomolog and Free Resolutions over Exterior Algebras

In this paper we derive an explicit version of the Bernstein-Gel'fand-Gel'fand (BGG) correspondence between bounded complexes of coherent sheaves on projective space and minimal doubly infinite free resolutions over its ``Koszul dual'' exterior algebra. This leads to an efficient method for machine computation of the cohomology of sheaves. Among the facts about the BGG correspondence that we derive is that taking homology of a complex of sheaves corresponds to taking the ``linear part'' of a resolution over the exterior algebra. Using these results we give a constructive proof of the existence…

通过弯曲 BGG 对应对 Koszul 复形上的厚子范畴进行分类

Classifying thick subcategories over a Koszul complex via the curved BGG correspondence

本文利用弯曲 BGG 对应及完美弯曲 dg 模的厚张量子模分类，刻画了正则环中任意元素列表的 Koszul 复形上有界 dg 模导出范畴的厚子范畴，并恢复 Stevenson、Hopkins–Neeman 等结果。

外代数上的 Schreyer 分解

Schreyer Resolutions over the Exterior Algebra

本文改编 Schreyer 算法，利用相对 Gröbner 基计算外代数上的自由分解，并应用于射影空间相干层上同调，同时探讨了并行实现的可能性。

Sheaf Cohomology and Free Resolutions over Exterior Algebras

In this paper we study the Bernstein-Gel'fand-Gel'fand (BGG) correspondence linking sheaves on a projective space to graded modules over an exterior algebra. We give an explicit construction of a Beilinson monad for a sheaf on projective space. The explicitness allows us to to prove two conjectures about the morphisms in the monad. We also construct all the monads for a sheaf that can be built from sums of line bundles. A large subclass, containing many monads introduced by others, are uniquely characterized by simple numerical data. Our methods also yield an efficient method for machine compu…

Castelnuovo-Mumford regularity for complexes and weakly Koszul modules

Let A be a noetherian AS regular Koszul quiver algebra (if A is commutative, it is essentially a polynomial ring), and grA the category of finitely generated graded left A-modules. Following Jorgensen, we define the Castelnuovo-Mumford regularity reg(X) of a complex X \in D^b(grA) in terms of the local cohomologies or the minimal projective resolution of X. Let A^! be the quadratic dual ring of A. For the Koszul duality functor DG : D^b(grA) -> D^b(grA^!), we have reg(X) = max {i | H^i(DG (X)) \ne 0}. Using these concepts, we study weakly Koszul modules (= componentwise linear modules) over A^…

The Horrocks correspondence for coherent sheaves on projective spaces

We establish an equivalence between the stable category of coherent sheaves (satisfying a mild restriction) on a projective space and the homotopy category of a certain class of minimal complexes of free modules over the exterior algebra Koszul dual to the homogeneous coordinate algebra of the projective space. We also relate these complexes to the Tate resolutions of the respective sheaves. In this way, we extend from vector bundles to coherent sheaves the results of Coandă and Trautmann [Trans. AMS 385 (2005)], which interpret in terms of the BGG correspondence the results of Trautmann [Math…