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There is a well known bijective correspondence between isomorphism classes of polystable vector bundles $E$ with $c_i(E)=0$ for $i\geq 1$ on a smooth complex projective variety and equivalence classes of unitary representations of the…

Algebraic Geometry · Mathematics 2012-02-07 Indranil Biswas , Amit Hogadi

For a continuous field of the Cuntz algebra over a finite CW complex, we introduce a topological invariant, which is an element in Dadarlat-Pennig's generalized cohomology group, and prove that the invariant is trivial if and only if the…

Operator Algebras · Mathematics 2020-02-18 Taro Sogabe

For a countable group $G$ we construct a small, idempotent complete, symmetric monoidal, stable $\infty$-category $\mathrm{KK}^{G}_{\mathrm{sep}}$ whose homotopy category recovers the triangulated equivariant Kasparov category of separable…

Operator Algebras · Mathematics 2025-12-03 Ulrich Bunke , Alexander Engel , Markus Land

We introduce the notion of groupoid pre-equivalences and prove that they give rise to groupoid equivalences by taking certain quotients. Then, given an equivalence of Fell bundles $\mathscr{B}$ and $\mathscr{C}$ and another equivalence…

Operator Algebras · Mathematics 2022-08-03 Anna Duwenig , Boyu Li

We define the Zappa-Sz\'{e}p product of a Fell bundle by a groupoid, which turns out to be a Fell bundle over the Zappa-Sz\'{e}p product of the underlying groupoids. Under certain assumptions, every Fell bundle over the Zappa-Sz\'{e}p…

Operator Algebras · Mathematics 2021-10-19 Anna Duwenig , Boyu Li

It is shown that every quantum principal bundle with a compact structure group is a Hopf-Galois extension. This property naturally extends to the level of general differential structures, so that every differential calculus over a quantum…

q-alg · Mathematics 2008-02-03 Mico Durdevic

This paper explores a new perspective on the universality of the vertical lift in tangent categories by presenting a categorification of the dimension of smooth manifolds. The universality of the vertical lift is a key part of the axioms of…

Category Theory · Mathematics 2026-02-18 Florian Schwarz

We show that a weakly integral braided fusion category C such that every simple object of C has Frobenius-Perron dimension at most 2 is solvable. In addition, we prove that such a fusion category is group-theoretical in the extreme case…

Quantum Algebra · Mathematics 2012-05-14 Sonia Natale , Julia Yael Plavnik

In this note we investigate the simplicial volume of fiber bundles with connected structure group. We are able to show that if the structure group is either compact or a Lie group, or if the fiber is aspherical that the simplicial volume of…

Algebraic Topology · Mathematics 2024-04-24 Thorben Kastenholz

We consider the construction of the basic bundle gerbe on SU(n) introduced by Meinrenken and show that it extends to a range of groups with unitary actions on a Hilbert space including U(n), diagonal tori and the Banach Lie group of unitary…

Differential Geometry · Mathematics 2009-11-13 Michael K Murray , Danny Stevenson

Let S be a K3 surface and assume for simplicity that it does not contain any (-2)-curve. Using coherent systems, we express every non-simple Lazarsfeld-Mukai bundle on S as an extension of two sheaves of some special type, that we refer to…

Algebraic Geometry · Mathematics 2014-10-17 Margherita Lelli-Chiesa

We formalize the ``metric bundle'' viewpoint by defining, for any smooth $n$--manifold $M$, the open fiberwise cones $\mathcal{G}^{p,q}\subset S^2\Tstar M$ of nondegenerate symmetric bilinear forms with fixed signature $(p,q)$, and we…

Differential Geometry · Mathematics 2025-10-21 Shouvik Datta Choudhury

Given any unital, finite, classifiable C$^*$-algebra $A$ with real rank zero and any compact simplex bundle with the fibre at zero being homeomorphic to the space of tracial states on $A$, we show that there exists a flow on $A$ realising…

Operator Algebras · Mathematics 2024-11-18 Robert Neagu

We prove the existence of a universal braided compact quantum group acting on a graph $\mathrm{C}^*$-algebra in the category of $\mathbb{T}$-$\mathrm{C}^*$-algebras with a twisted monoidal structure, in the spirit of the seminal work of S.…

Operator Algebras · Mathematics 2024-08-12 Suvrajit Bhattacharjee , Soumalya Joardar , Sutanu Roy

Let $G$ be a Lie group, with an invariant non-degenerate symmetric bilinear form on its Lie algebra, let $\pi$ be the fundamental group of an orientable (real) surface $M$ with a finite number of punctures, and let $\bold C$ be a family of…

dg-ga · Mathematics 2008-02-03 K. Guruprasad , J. Huebschmann , L. Jeffrey , A. Weinstein

We show that any closed model category of simplicial algebras over an algebraic theory is Quillen equivalent to a proper closed model category. By ``simplicial algebra'' we mean any category of algebras over a simplicial algebraic theory,…

Algebraic Topology · Mathematics 2008-12-05 Charles Rezk

Let $A$ be a separable simple exact ${\cal Z}$-stable $C^*$-algebra. We show that the unitay group of ${\tilde A}$ has the cancellation property. If $A$ has continuous scale, the Cuntz semigroup of $\tilde A$ has the strict comparison…

Operator Algebras · Mathematics 2021-05-05 Huaxin Lin

We classify the reflexive modules of rank one over rational and minimally elliptic singularities. Equivalently, we classify full line bundles on the resolutions of rational and minimally elliptic singularities. As an application, we…

Algebraic Geometry · Mathematics 2023-05-11 András Némethi , Agustín Romano-Velázquez

A simplicial set is said to be non-singular if the representing map of each non-degenerate simplex is degreewise injective. The inclusion into the category of simplicial sets, of the full subcategory whose objects are the non-singular…

Algebraic Topology · Mathematics 2020-01-17 Vegard Fjellbo

This submission replaces the arXiv:1012.5381 submission with the same title, which had been withdrawn as it contained a mistake, repaired in this submission: on $X$ projective smooth over an algebraically closed field of characteristic…

Algebraic Geometry · Mathematics 2011-12-21 Hélène Esnault , Xiaotao Sun