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We define the categorical cohomology of a k-graph \Lambda\ and show that the first three terms in this cohomology are isomorphic to the corresponding terms in the cohomology defined in our previous paper. This leads to an alternative…

Operator Algebras · Mathematics 2013-08-15 Alex Kumjian , David Pask , Aidan Sims

We argue that the $q$-deformed spin-1 AKLT Hamiltonian should be regarded as a representative of a symmetry protected topological phase. Even though it fails to exhibit any of the standard symmetries known to protect the Haldane phase it…

Strongly Correlated Electrons · Physics 2020-09-16 Thomas Quella

We study the K-theory of ring C*-algebras associated to rings of integers in global function fields with only one single infinite place. First, we compute the torsion-free part of the K-groups of these ring C*-algebras. Secondly, we show…

Operator Algebras · Mathematics 2011-04-07 Xin Li

We show that unital simple C*-algebras with tracial topological rank zero which are locally approximated by subhomogeneous C^-algebras can be classified by their ordered $K$-theory. We apply this classification result to show that certain…

Operator Algebras · Mathematics 2007-05-23 Huaxin Lin

We study non-interacting electrons in disordered one-dimensional materials which exhibit a spectral gap, in each of the ten Altland-Zirnbauer symmetry classes. We define an appropriate topology on the space of Hamiltonians so that the…

Mathematical Physics · Physics 2023-07-04 Jui-Hui Chung , Jacob Shapiro

Brown and Goodearl stated a conjecture that provides an explicit description of the topology of the spectra of quantum algebras. The conjecture takes on a more explicit form if there exist separating Ore sets for all incident pairs of torus…

Quantum Algebra · Mathematics 2017-12-06 Siân Fryer , Milen Yakimov

In this paper we introduce a homotopy theoretic technique for proving that the $K$-theoretic assembly map is an equivalence. It is an extension of the methods used to prove split injectivity of the assembly and applies to any geometrically…

Algebraic Topology · Mathematics 2026-01-19 Gunnar Carlsson , Boris Goldfarb

We discuss the thermal (or gravitational) responses in topological superconductors and in topological phases in general. Such thermal responses (as well as electromagnetic responses for conserved charge) provide a definition of topological…

Mesoscale and Nanoscale Physics · Physics 2013-12-06 Akira Furusaki , Naoto Nagaosa , Kentaro Nomura , Shinsei Ryu , Tadashi Takayanagi

k-graphs are higher-rank analogues of directed graphs which were first developed to provide combinatorial models for operator algebras of Cuntz-Krieger type. Here we develop the theory of covering spaces for k-graphs, obtaining a…

Operator Algebras · Mathematics 2008-05-23 David Pask , John Quigg , Iain Raeburn

In this paper, we study multiplicative structures on the K-theory of the core $A:=C^*(E)^{U(1)}$ of the C*-algebra $C^*(E)$ of a directed graph $E$. In the first part of the paper, we study embeddings $E\to E\times E$ that induce a…

K-Theory and Homology · Mathematics 2026-04-15 Francesco D'Andrea

We study the class of simple C*-algebras introduced by Villadsen in his pioneering work on perforated ordered K-theory. We establish six equivalent characterisations of the proper subclass which satisfies the strong form of Elliott's…

Operator Algebras · Mathematics 2007-05-23 Andrew S. Toms , Wilhelm Winter

The multipullback quantization of complex projective spaces lacks the naive quantum CW-complex structure because the quantization of an embedding of the $n$-skeleton into the $(n+1)$-skeleton does not exist. To overcome this difficulty, we…

K-Theory and Homology · Mathematics 2022-01-03 Francesco D'Andrea , Piotr M. Hajac , Tomasz Maszczyk , Albert Sheu , Bartosz Zielinski

The aim of this paper is to describe the topological $K$-ring, in terms of generators and relations of a flag Bott manifold. We apply our results to give a presentation for the topological K-ring and hence the Grothendieck ring of algebraic…

Algebraic Topology · Mathematics 2026-01-15 Bidhan Paul , Vikraman Uma

We unite elements of category theory, K-theory, and geometric group theory, by defining a class of groups called $k$-cube groups, which act freely and transitively on the product of $k$ trees, for arbitrary $k$. The quotient of this action…

Operator Algebras · Mathematics 2024-01-12 Sam A. Mutter , Aura-Cristiana Radu , Alina Vdovina

We prove an analogue of the Gabriel--Quillen embedding theorem for exact $\infty$-categories, giving rise to a presentable version of Klemenc's stable envelope of an exact $\infty$-category. Moreover, we construct a symmetric monoidal…

Algebraic Topology · Mathematics 2026-03-23 Marius Nielsen , Christoph Winges

Algebraic K-theory is the stable homotopy theory of homotopy theories, and it interacts with algebraic structures accordingly. In particular, we prove the Deligne Conjecture for algebraic K-theory.

K-Theory and Homology · Mathematics 2014-07-17 C. Barwick

Using a result of Vdovina, we may associate to each complete connected bipartite graph $\kappa$ a $2$-dimensional square complex, which we call a tile complex, whose link at each vertex is $\kappa$. We regard the tile complex in two…

Combinatorics · Mathematics 2021-02-18 S. A. Mutter

We develop differential algebraic K-theory of regular arithmetic schemes. Our approach is based on a new construction of a functorial, spectrum level Beilinson regulator using differential forms. We construct a cycle map which represents…

Number Theory · Mathematics 2015-09-28 Ulrich Bunke , Georg Tamme

For a $C^{*}$-category with a strict $G$-action we construct examples of equivariant coarse homology theories. To this end we first introduce versions of Roe categories of objects in $C^{*}$-categories which are controlled over bornological…

K-Theory and Homology · Mathematics 2023-06-21 Ulrich Bunke , Alexander Engel

Clausen--Scholze introduced the notion of solid spectrum in their condensed mathematics program. We demonstrate that the solidification of algebraic $K$-theory recovers two known constructions: the semitopological $K$-theory of a real…

K-Theory and Homology · Mathematics 2024-09-04 Ko Aoki