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In this paper the space of almost commuting elements in a Lie group is studied through a homotopical point of view. In particular a stable splitting after one suspension is derived for these spaces and their quotients under conjugation. A…

Algebraic Topology · Mathematics 2015-05-20 Alejandro Adem , Frederick R. Cohen , Jose Manuel Gomez

A short proof of a conjecture of Kropholler is given. This gives a relative version of Stallings' Theorem on the structure of groups with more than one end. A generalisation of the Almost Stability Theorem is also obtained, that gives…

Group Theory · Mathematics 2015-01-05 M. J. Dunwoody

We apply our previous work on the relation between groupoid homology and K-theory to Smale spaces. More precisely, we consider the unstable equivalence relation of a Smale space with totally disconnected stable sets, and prove that the…

K-Theory and Homology · Mathematics 2023-11-28 Valerio Proietti , Makoto Yamashita

We prove a decomposition theorem for the equivariant K-theory of actions of affine group schemes G of finite type over a field on regular separated noetherian algebraic spaces, under the hypothesis that the actions have finite geometric…

Algebraic Geometry · Mathematics 2007-05-23 Gabriele Vezzosi , Angelo Vistoli

A theorem is proved to verify incremental stability of a feedback system via a homotopy from a known incrementally stable system. A first corollary of that result is that incremental stability may be verified by separation of Scaled…

Optimization and Control · Mathematics 2024-12-03 Thomas Chaffey , Andrey Kharitenko , Fulvio Forni , Rodolphe Sepulchre

We show that in $K$-theory-like categories many corner embeddings into a discrete algebra of compact operators are invertible, and consequently functors on splitexact algebraic $KK$-theory are faithful if and only if they are faithful on…

K-Theory and Homology · Mathematics 2025-01-22 Bernhard Burgstaller

Lipshitz-Sarkar defined a stable homotopy type refining Khovanov homology, producing cohomology operations $\text{Sq}^i$ on the Khovanov homology $Kh(L)$ of a link $L$. Later, Mor\'an proposed a sequence of cup-i products on the…

Geometric Topology · Mathematics 2026-03-18 Advika Rajapakse

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

We introduce a fairly general concept of functional equation for $k$-tuples of functions $f_1,\dots,f_k\colon X \to Y$ between arbitrary sets. The homomorphy equations for mappings between groups and other algebraic systems, as well as…

Functional Analysis · Mathematics 2015-10-19 Pavol Zlatoš

By introducing a notion of smooth connection for unbounded $KK$-cycles, we show that the Kasparov product of such cycles can be defined directly, by an algebraic formula. In order to achieve this it is necessary to develop a framework of…

K-Theory and Homology · Mathematics 2014-04-18 Bram Mesland

We introduce a slight modification of the usual equivariant $KK$-theory. We use this to give a $KK$-theoretical proof of an equivariant index theorem for Dirac-Schrodinger operators on a non-compact manifold of nowhere positive curvature.…

K-Theory and Homology · Mathematics 2023-06-28 Y. Abdolmaleki , D. Kucerovsky

We investigate a class of nonlocal integro-differential equations involving Hilfer fractional derivatives and almost sectorial operators. We prove existence results by applying Schauder's fixed point technique. Moreover, we show fundamental…

Spectral Theory · Mathematics 2021-03-09 Kulandhaivel Karthikeyan , Amar Debbouche , Delfim F. M. Torres

We provide a mathematical realization of a conjecture by Kitaev, on the basis of the operator-algebraic formulation of infinite quantum spin systems. Our main results are threefold. First, we construct an $\Omega$-spectrum $\mathit{IP}_*$…

Mathematical Physics · Physics 2025-12-30 Yosuke Kubota

Given a henselian pair $(R, I)$ of commutative rings, we show that the relative $K$-theory and relative topological cyclic homology with finite coefficients are identified via the cyclotomic trace $K \to \mathrm{TC}$. This yields a…

K-Theory and Homology · Mathematics 2020-07-21 Dustin Clausen , Akhil Mathew , Matthew Morrow

We show that Klemenc's stable envelope of exact $\infty$-categories induces an equivalence between stable $\infty$-categories with a bounded heart structure and weakly idempotent complete exact $\infty$-categories. Moreover, we generalise…

K-Theory and Homology · Mathematics 2025-12-01 Victor Saunier , Christoph Winges

Based on the three-ball inequality and the doubling inequality established in [23], we quantify the strong unique continuation established by Koch and Tataru [21] for elliptic operators with unbounded lower-order coefficients. We also…

Analysis of PDEs · Mathematics 2025-03-27 Mourad Choulli

We define a theory of Goodwillie calculus for enriched functors from finite pointed simplicial G-sets to symmetric G-spectra, where G is a finite group. We extend a notion of G-linearity suggested by Blumberg to define stably excisive and…

Algebraic Topology · Mathematics 2019-02-20 Emanuele Dotto

We consider operations between two multiplicative, complex orientable cohomology theories. Under suitable hypotheses, we construct a map from unstable to stable operations, left-inverse to the usual map from stable to unstable operations.…

Algebraic Topology · Mathematics 2016-01-20 Andrew Stacey , Sarah Whitehouse

We introduce smooth atlas stratified spaces. We show that this class is closed under cartesian products; consequently, it is possible to define fiber bundles of smooth atlas stratified spaces. We describe the resolution of such a space to a…

Differential Geometry · Mathematics 2025-05-22 Pierre Albin , Markus Banagl , Paolo Piazza

This is a survey article with the goal to advertise spectrum valued versions of $K$- and $KK$- theory for $C^{*}$-algebras via a (stable and symmetric monoidal) $\infty$-categorical enhancement of Kasparov's classical $KK$-theory. The main…

Operator Algebras · Mathematics 2023-11-30 Ulrich Bunke , Markus Land , Ulrich Pennig