Results 41 to 50 of about 181,507 (166)
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
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THE DP-RANK OF ABELIAN GROUPS [PDF]
The Journal of Symbolic Logic, 2019 AbstractAn equation to compute the dp-rank of any abelian group is given. It is also shown that its dp-rank, or more generally that of any one-based group, agrees with its Vapnik–Chervonenkis density. Furthermore, strong abelian groups are characterised to be precisely those abelian groups A such that there are only finitely many primes p such that the
Halevi, Yatir, Palacín Cruz, Daniel
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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
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Journal of Algebra, 2009 AbstractLetE(G)=End(G)/N(End(G)). Our goal in this paper is to study direct sum decompositions of certain reduced torsion-free finite rank (rtffr) abelian groups by introducing an ideal τ of E(G) called a conductor of G. This ideal induces a natural ring decomposition E(G)=E(G)(τ)×E(G)τ and a natural direct sum decomposition G=G(τ)⊕Gτ for an rtffr ...
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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
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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
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Journal of Algebra, 2015 In this paper we study the colimit N_2(G) of abelian subgroups of a discrete group G. This group is the fundamental group of a subspace B(2,G) of the classifying space BG. We describe N_2(G) for certain groups, and apply our results to study the homotopy type of the space B(2,G). We give a list of classes of groups for which B(2,G) is not an Eilenberg--
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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
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On the Terwilliger Algebra of the Group Association Scheme of the Symmetric Group Sym ( 7 )
Journal of Combinatorial Designs, Volume 33, Issue 7, Page 261-274, July 2025.ABSTRACT Terwilliger algebras are finite‐dimensional semisimple algebras that were first introduced by Paul Terwilliger in 1992 in studies of association schemes and distance‐regular graphs. The Terwilliger algebras of the conjugacy class association schemes of the symmetric groups Sym ( n ), for 3 ≤ n ≤ 6, have been studied and completely determined ...
Allen Herman +2 more
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Sparse graph signals – uncertainty principles and recovery
GAMM-Mitteilungen, Volume 48, Issue 2, June 2025.ABSTRACT We study signals that are sparse either on the vertices of a graph or in the graph spectral domain. Recent results on the algebraic properties of random integer matrices as well as on the boundedness of eigenvectors of random matrices imply two types of support size uncertainty principles for graph signals.
Tarek Emmrich +2 more
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