Results 81 to 90 of about 12,511,421 (301)

The birational geometry of GIT quotients

Bulletin of the London Mathematical Society, EarlyView.
Abstract Geometric invariant theory (GIT) produces quotients of algebraic varieties by reductive groups. If the variety is projective, this quotient depends on a choice of polarisation; by work of Dolgachev–Hu and Thaddeus, it is known that two quotients of the same variety using different polarisations are related by birational transformations.
Ruadhaí Dervan, Rémi Reboulet
wiley   +1 more source

Hereditary Coreflective Subcategories in Certain Categories of Abelian Semitopological Groups

Axioms, 2019
Let A be an epireflective subcategory of the category of all semitopological groups that consists only of abelian groups. We describe maximal hereditary coreflective subcategories of A that are not bicoreflective in A in the case that ...
Veronika Pitrová
doaj   +1 more source

Free topological groups and the projective dimension of a locally compact abelian group

, 1973
It is shown that a free topological group on a k.space is a k.-space. Using this it is proved that if X is a k.-group then it is a quotient of a free topological group by a free topological group.
J. Mack, S. Morris, E. Ordman
semanticscholar   +1 more source

On t-extensions of abelian groups [PDF]

, 2014
Let G and C be two discrete abelian groups. It is known that Pext(C,G) is a subgroup of Ext(C,G). In this paper, we introduce the t-extensions of G by C. We will show that the set of all t-extensions of G by C is a subgroup of Ext(C,G) which contains Pext(C,G).
Aliakbar Alijani, Hossein Sahleh
openaire   +2 more sources

Spectra of subrings of cohomology generated by characteristic classes for fusion systems

Bulletin of the London Mathematical Society, EarlyView.
Abstract If F$\mathcal {F}$ is a saturated fusion system on a finite p$p$‐group S$S$, we define the Chern subring Ch(F)${\operatorname{Ch}}(\mathcal {F})$ of F$\mathcal {F}$ to be the subring of H∗(S;Fp)$H^*(S;{\mathbb {F}}_p)$ generated by Chern classes of F$\mathcal {F}$‐stable representations of S$S$. We show that Ch(F)${\operatorname{Ch}}(\mathcal {
Ian J. Leary, Jason Semeraro
wiley   +1 more source

Structure of Wittrings and Quotients of Abelian Group Rings

, 1972
In this paper we give a detailed exposition of some of the results announced in [18]. The primary motivation for this work is Witt's observation [31, Satz 7] that if F is a field of characteristic #72, his ring 1V(F) of classes of anisotropic quadratic ...
Manfred Knebusch, A. Rosenberg, R. Ware
semanticscholar   +1 more source

Strong Reflexivity of Abelian Groups [PDF]

Czechoslovak Mathematical Journal, 2001
A reflexive topological group G is called strongly reflexive if each closed sub-group and each Hausdorff quotient of the group G and of its dual group is reflexive. In this paper we establish the adequate concept of strong reflexivity for convergence groups and we prove that the product of countable many locally compact topological groups and ...
Bruguera Padró, Maria Montserrat, Chasco Ugarte, Maria Jesús   +1 more
openaire   +3 more sources

Étale motives of geometric origin

Bulletin of the London Mathematical Society, EarlyView.
Abstract Over qcqs finite‐dimensional schemes, we prove that étale motives of geometric origin can be characterised by a constructibility property which is purely categorical, giving a full answer to the question ‘Do all constructible étale motives come from geometry?’ which dates back to Cisinski and Déglise's work.
Raphaël Ruimy, Swann Tubach
wiley   +1 more source

Connections on non-abelian Gerbes and their Holonomy [PDF]

, 2013
We introduce an axiomatic framework for the parallel transport of connections on gerbes. It incorporates parallel transport along curves and along surfaces, and is formulated in terms of gluing axioms and smoothness conditions.
Schreiber, Urs, Waldorf, Konrad
core   +1 more source

Twists of twisted generalized Weyl algebras

Bulletin of the London Mathematical Society, EarlyView.
Abstract We study graded twisted tensor products and graded twists of twisted generalized Weyl algebras (TGWAs). We show that the class of TGWAs is closed under these operations assuming mild hypotheses. We generalize a result on cocycle equivalence among multiparameter quantized Weyl algebras to the setting of TGWAs.
Jason Gaddis, Daniele Rosso
wiley   +1 more source