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We show that for a gradable finite dimensional algebra the perfect complexes and bounded derived category cannot be distinguished by homotopy invariants.

K-Theory and Homology · Mathematics 2024-05-10 Sira Gratz , Theo Raedschelders , Špela Špenko , Greg Stevenson

A detailed proof is given of a theorem describing the centraliser of a transitive permutation group, with applications to automorphism groups of objects in various categories of maps, hypermaps, dessins, polytopes and covering spaces, where…

Group Theory · Mathematics 2018-05-25 Gareth A. Jones

We introduce and study a notion of cylinder coherator similar to the notion of Grothendieck coherator which define more flexible notion of weak infinity groupoids. We show that each such cylinder coherator produces a combinatorial…

Category Theory · Mathematics 2016-09-16 Simon Henry

Suppose we are given a graph and want to show a property for all its cycles (closed chains). Induction on the length of cycles does not work since sub-chains of a cycle are not necessarily closed. This paper derives a principle reminiscent…

Logic · Mathematics 2020-07-01 Nicolai Kraus , Jakob von Raumer

We classify homotopes of classical symmetric spaces (studied in Part I of this work). Our classification uses the fibered structure of homotopes: they are fibered as symmetric spaces, with flat fibers, over a non-degenerate base; the base…

Differential Geometry · Mathematics 2012-03-06 Wolfgang Bertram , Pierre Bieliavsky

Let $X$ be a locally symmetric space $\Gamma\backslash G/K$ where $G$ is a connected non-compact semisimple real Lie group with trivial centre, $K$ is a maximal compact subgroup of $G$, and $\Gamma\subset G$ is a torsion-free irreducible…

Algebraic Topology · Mathematics 2015-05-20 Arghya Mondal , Parameswaran Sankaran

The original Smale Conjecture asserted that the inclusion of the group O(4) of isometries of the round 3-sphere S into the full diffeomorphism group Diff(S) is a homotopy equivalence. The (Generalized) Smale Conjecture asserts that the…

Geometric Topology · Mathematics 2007-05-23 Sungbok Hong , Darryl McCullough , J. Hyam Rubinstein

We show that discrete and classical homotopy theories are equivalent after localizing at n-equivalences for any non-negative integer n. By constructing an explicit homotopy inverse to the graph nerve functor associating an n-fibrant cubical…

Algebraic Topology · Mathematics 2026-02-24 Daniel Carranza , Chris Kapulkin

Generically, the set of points along which two non-singular vector fields on the three-sphere are positively (resp. negatively) collinear form a link. We prove that the two vector fields are homotopic if and only if the linking number of…

Dynamical Systems · Mathematics 2007-05-23 Emmanuel Dufraine

Gerbes are locally connected presheaves of groupoids. They are classified up to local weak equivalence by path components in a 2-cocycle category taking values in all sheaves of groups, their isomorphisms and homotopies. If F is a full…

Algebraic Topology · Mathematics 2007-05-23 J. F. Jardine

We show that the automorphism group of every zero entropy infinite shift admits a "drift" homomorphism to $(\mathbb{R},+)$ that maps the shift map to 1. This homomorphism arises as the expectation, under an invariant measure, of a cocycle…

Dynamical Systems · Mathematics 2022-02-21 Omer Tamuz

We endow categories of non-symmetric operads with natural model structures. We work with no restriction on our operads and only assume the usual hypotheses for model categories with a symmetric monoidal structure. We also study categories…

Algebraic Topology · Mathematics 2011-05-31 Fernando Muro

In this paper we propose an approach to homotopical algebra where the basic ingredient is a category with two classes of distinguished morphisms: strong and weak equivalences. These data determine the cofibrant objects by an extension…

Algebraic Topology · Mathematics 2008-09-18 F. Guillen Santos , V. Navarro , P. Pascual , Agusti Roig

The homotopy theory of higher categorical structures has become a relevant part of the machinery of algebraic topology and algebraic K-theory, and this paper contains contributions to the study of the relationship between B\'enabou's…

Category Theory · Mathematics 2014-04-11 A. M. Cegarra , B. A. Heredia , J. Remedios

A reductive homogeneous space $G/H$ is always diffeomorphic to the normal bundle of an orbit of a maximal compact subgroup of $G$. We prove that if $G/H$ admits compact quotients, then the sphere bundle associated to this normal bundle is…

Geometric Topology · Mathematics 2026-01-12 Fanny Kassel , Yosuke Morita , Nicolas Tholozan

The goal of this thesis is to prove that $\pi_4(S^3) \simeq \mathbb{Z}/2\mathbb{Z}$ in homotopy type theory. In particular it is a constructive and purely homotopy-theoretic proof. We first recall the basic concepts of homotopy type theory,…

Algebraic Topology · Mathematics 2016-06-21 Guillaume Brunerie

In this paper, we study a construction of homotopy invariants of open or closed covers, where the homotopy class is defined relative to a pair $(V,r)$, with $V$ a finite set of points in $\mathbb{R}^d$ and $r$ a point in the interior of…

Combinatorics · Mathematics 2025-10-21 Mikhail V. Bludov

We reduce the isomorphism problem for undirected graphs without loops to the isomorphism problems for a class of finite dimensional $2$-step nilpotent Lie algebras over a field and for a class of finite $p$-groups. We show that the…

Group Theory · Mathematics 2020-08-03 Ruvim Lipyanski , Natalia Vanetik

For a finite quiver without sources or sinks, we prove that the homotopy category of acyclic complexes of injective modules over the corresponding finite dimensional algebra with radical square zero is triangle equivalent to the derived…

Representation Theory · Mathematics 2015-12-09 Xiao-Wu Chen , Dong Yang

The theory of condensed mathematics by Dustin Clausen and Peter Scholze claims that topological spaces should be replaced by the definition of condensed sets. The main purpose of this paper is to investigate in which way the theory of…

Algebraic Topology · Mathematics 2021-05-18 Catrin Mair