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This article establishes a geometric Satake equivalence for affine Kac-Moody groups as an equivalence of abelian semisimple categories over algebraically closed fields. We define a well-behaved category of equivariant sheaves on the double…

Representation Theory · Mathematics 2025-10-22 Alexis Bouthier , Eric Vasserot

Linear categories naturally have several identification relations : isomorphisms, categorical equivalences and Morita equivalences. In this thesis, we construct the classifying stacks for these three relations ($\ukcatiso$, $\ukcateq$,…

Algebraic Geometry · Mathematics 2007-05-23 Mathieu Anel

Bott and Taubes used integrals over configuration spaces to produce finite-type a.k.a. Vassiliev knot invariants. Cattaneo, Cotta-Ramusino and Longoni then used these methods together with graph cohomology to construct "Vassiliev classes"…

Geometric Topology · Mathematics 2021-06-23 Robin Koytcheff

We study the arithmetic of abelian varieties over $K=k(t)$ where $k$ is an arbitrary field. The main result relates Mordell-Weil groups of certain Jacobians over $K$ to homomorphisms of other Jacobians over $k$. Our methods also yield…

Number Theory · Mathematics 2011-02-21 Douglas Ulmer

A equivalence relation, preserving the Chern-Weil form, is defined between connections on a complex vector bundle. Bundles equipped with such an equivalence class are called Structured Bundles, and their isomorphism classes form an abelian…

Algebraic Topology · Mathematics 2008-10-29 James Simons , Dennis Sullivan

In this paper we consider the question of what abelian groups can arise as the $K$-theory of $\mathrm{C}^*$-algebras arising from minimal dynamical systems. We completely characterize the $K$-theory of the crossed product of a space $X$…

Operator Algebras · Mathematics 2020-12-22 Robin J. Deeley , Ian F. Putnam , Karen R. Strung

We introduce a cohomological invariant arising from a class in nonabelian cohomology. This invariant generalizes the Dixmier-Douady class and encodes the obstruction to a C*-algebra bundle being the fixed-point algebra of a gauge action. As…

Operator Algebras · Mathematics 2011-11-18 Ezio Vasselli

We compare the K-theories of symplectic quotients with respect to a compact connected Lie group and with respect to its maximal torus, and in particular we give a method for computing the former in terms of the latter. More specifically,…

Symplectic Geometry · Mathematics 2007-05-23 Megumi Harada , Gregory D. Landweber

Connectivity is a homotopy invariant property of a separable C*-algebra A which has three important consequences: absence of nontrivial projections, quasidiagonality and realization of the Kasparov group KK(A,B) as homotopy classes of…

Operator Algebras · Mathematics 2023-11-27 Marius Dadarlat , Ulrich Pennig , Andrew Schneider

A C_n-move is a local move on links defined by Habiro and Goussarov, which can be regarded as a `higher order crossing change'. We use Milnor invariants with repeating indices to provide several classification results for links up to…

Geometric Topology · Mathematics 2010-02-09 Jean-Baptiste Meilhan , Akira Yasuhara

This paper gives a Schur-Weyl duality approach to the representation theory of the affine Hecke algebras of type C with unequal parameters. The first step is to realize the affine braid group of type $C_k$ as the group of braids on $k$…

Representation Theory · Mathematics 2018-04-30 Zajj Daugherty , Arun Ram

We prove that any countable discrete and torsion free subgroup of a general linear group over an arbitrary field or a similar subgroup of an almost connected Lie group satisfies the integral algebraic K-theoretic (split) Novikov conjecture…

K-Theory and Homology · Mathematics 2015-08-05 Snigdhayan Mahanta

We construct an abelian category C and exact functors in C which on the Grothendieck group descend to the action of a simply-laced quantum group in its adjoint representation. The braid group action in the adjoint representation lifts to an…

Quantum Algebra · Mathematics 2007-05-23 Ruth Stella Huerfano , Mikhail Khovanov

We initiate the program of extending to higher-rank graphs ($k$-graphs) the geometric classification of directed graph $C^*$-algebras, as completed in the 2016 paper of Eilers, Restorff, Ruiz, and Sorensen [ERRS16]. To be precise, we…

Operator Algebras · Mathematics 2020-06-25 Caleb Eckhardt , Kit Fieldhouse , Daniel Gent , Elizabeth Gillaspy , Ian Gonzales , David Pask

We propose a new notion of unbounded $K\!K$-cycle, mildly generalising unbounded Kasparov modules, for which the direct sum is well-defined. To a pair $(A,B)$ of $\sigma$-unital $C^{*}$-algebras, we can then associate a semigroup…

K-Theory and Homology · Mathematics 2020-07-29 Koen van den Dungen , Bram Mesland

We introduce the notion of the action of a group on a labeled graph and the quotient object, also a labeled graph. We define a skew product labeled graph and use it to prove a version of the Gross-Tucker theorem for labeled graphs. We then…

Operator Algebras · Mathematics 2013-05-17 Teresa Bates , David Pask , Paulette Willis

We study the classification of group actions on C*-algebras up to equivariant KK-equivalence. We show that any group action is equivariantly KK-equivalent to an action on a simple, purely infinite C*-algebra. We show that a conjecture of…

K-Theory and Homology · Mathematics 2021-08-25 Ralf Meyer

We develop class field theory of curves over $p$-adic fields which extends the unramified theory of S. Saito. The class groups which approximate abelian \'etale fundamental groups of such curves are introduced in the terms of algebraic…

Number Theory · Mathematics 2008-03-18 Toshiro Hiranouchi

A quandle is a self-distributive algebraic structure that appears in quasi-group and knot theories. For each abelian group A and c \in A we define a quandle G(A, c) on \Z_3 \times A. These quandles are generalizations of a class of…

Rings and Algebras · Mathematics 2016-11-15 W. Edwin Clark , Mohamed Elhamdadi , Xiang-dong Hou , Masahico Saito , Timothy Yeatman

The notion of Vassiliev algebra in case of hanlebodies is developed. The analogues of the results of John Baez for links in handlebodies are proved. That means that there exists a one-to-one correspondence between the special class of…

q-alg · Mathematics 2012-02-22 V. V. Vershinin