We prove that the cohomology ring structure of the Hilbert scheme X [n] of n-points on a projective surface X is determined in a universal way by the cohomology ring of X. In particular, if there exists a ring isomorphism H ∗(X) → H∗(Y ) for two projective surfaces X and Y which matches the canonical classes, then the cohomology rings of the Hilbert schemes X [n] and Y [n] are isomorphic for ev...

‎‎we exhibit an explicit construction for the second cohomology group‎ ‎$h^2(l‎, ‎a)$ for a lie ring $l$ and a trivial $l$-module $a$‎. ‎we show how the elements of $h^2(l‎, ‎a)$ correspond one-to-one to the‎ ‎equivalence classes of central extensions of $l$ by $a$‎, ‎where $a$‎ ‎now is considered as an abelian lie ring‎. ‎for a finite lie‎ ‎ring $l$ we also show that $h^2(l‎, ‎c^*) cong m(l)$‎...

We compute the orbifold cohomology ring of the simplicial toric stack bundles. We give an example to show that the ordinary cohomology ring of the crepant resolution of a simplicial toric stack bundle is not necessarily isomorphic to its orbifold cohomology ring.

String theorists (notably Witten [W]) recently introduced the notion of a “quantum” deformation of the cohomology ring of a smooth projective variety X. This quantum deformation, or quantum cohomology ring, as it is often called, is an algebra over a formal-power-series ring which specializes to the ordinary cohomology ring, and which is defined in terms of intersection data (the Gromov-Witten ...

We study local cohomology of rings of global sections of sheafs on the Alexandrov space of a partially ordered set. We give a criterion for a splitting of the local cohomology groups into summands determined by the cohomology of the poset and the local cohomology of the stalks. The face ring of a rational pointed fan can be considered as the ring of global sections of a flasque sheaf on the fac...

We apply constructions from equivariant topology to Benson-Carlson resolutions and hence prove in (2.1) that the group cohomology ring of a nite group enjoys remarkable duality properties based on its global geometry. This recovers and generalizes the result of Benson-Carlson stating that a Cohen-Macaulay cohomology ring is automatically Gorenstein. We give an alternative approach to Tate cohom...

The theory of local homology modules was initiated by Matlis in 1974. It is a dual version of the theory of local cohomology modules. Mohammadi and Divaani-Aazar (2012) studied the connection between local homology and Gorenstein flat modules by using Gorenstein flat resolutions. In this paper, we introduce generalized local homology modules for complexes and we give several ways for computing ...

Let C be a smooth projective curve over the complex number field C. We investigate the structure of the cohomology ring of the quot schemes Quot(r, n), i.e., the moduli scheme of the quotient sheaves of O r C with length n. We obtain a filtration on H(Quot(r, n)), whose associated graded ring has a quite simple structure. As a corollary, we obtain a small generator of the ring. We also obtain a...

We study the ideals of the rational cohomology ring of the Hilbert scheme X [n] of n points on a smooth projective surface X . As an application, for a large class of smooth quasi-projective surfaces X , we show that every cup product structure constant of H∗(X ) is independent of n; moreover, we obtain two sets of ring generators for the cohomology ring H∗(X ). Similar results are established ...

Cohomology and cohomology ring of three-dimensional (3D) objects are topological invariants that characterize holes and their relations. Cohomology ring has been traditionally computed on simplicial complexes. Nevertheless, cubical complexes deal directly with the voxels in 3D images, no additional triangulation is necessary, facilitating efficient algorithms for the computation of topological ...