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We prove the existence of a model structure on the category of stratified simplicial sets whose fibrant objects are precisely $n$-complicial sets, which are a proposed model for $(\infty,n)$-categories, based on previous work of Verity and…

Algebraic Topology · Mathematics 2020-06-03 Viktoriya Ozornova , Martina Rovelli

In [BaSc2] the authors introduced a much weaker homotopical structure than a model category, called a "weak cofibration category". We further showed that a small weak cofibration category induces in a natural way a model category structure…

Algebraic Topology · Mathematics 2016-10-27 Ilan Barnea , Tomer M. Schlank

In this paper, we classify finite categories with two objects such that one of the endomorphism monoids is a group. We prove that having a group on one side affects the structure of the other endomorphism monoid, and we prove that it is…

Category Theory · Mathematics 2022-10-04 Najwa Ghannoum , Carlos Simpson

Much of the homotopical and homological structure of the categories of chain complexes and topological spaces can be deduced from the existence and properties of the 'simple' functors Tot : {double chain complexes} -> {chain complexes} and…

Algebraic Geometry · Mathematics 2008-04-15 Beatriz Rodriguez Gonzalez

Given an affine Poisson algebra, that is singular one may ask whether there is an associated symplectic form. In the smooth case the answer is obvious: for the symplectic form to exist the Poisson tensor has to be invertible. In the…

Algebraic Geometry · Mathematics 2025-02-11 Hans-Christian Herbig , William Osnayder Clavijo Esquivel , Christopher Seaton

Theorem (after Giraud, SGA 4): Suppose $A$ is a simplicial category. The following conditions are equivalent: (i) There is a cofibrantly generated closed model category $M$ such that $A$ is equivalent to the Dwyer-Kan simplicial…

Algebraic Topology · Mathematics 2007-05-23 Carlos Simpson

Using Dugger's construction of universal model categories, we produce replacements for simplicial and combinatorial symmetric monoidal model categories with better operadic properties. Namely, these replacements admit a model structure on…

Algebraic Topology · Mathematics 2024-12-31 Haldun Özgür Bayındır , Boris Chorny

In this paper, we study the structure of a generalized near-group fusion category and classified it when it is slightly degenerate.

Quantum Algebra · Mathematics 2019-03-22 Jingcheng Dong

In this article we give a classification of the binary, simple, $\omega$-categorical structures with SU-rank 1 and trivial pregeometry. This is done both by showing that they satisfy certain extension properties, but also by noting that…

Logic · Mathematics 2017-04-11 Ove Ahlman

We give a fully constructive proof that there is a proper cartesian $\omega$-combinatorial model structure on the category of simplicial sets, whose generating cofibrations and trivial cofibrations are the usual boundary inclusion and horn…

Category Theory · Mathematics 2019-05-16 Simon Henry

Given a map of simplicial topological spaces, mild conditions on degeneracies and the levelwise maps imply that the geometric realization of the simplicial map is a cofibration. These conditions are not formal consequences of model category…

Algebraic Topology · Mathematics 2018-01-31 Gabe Angelini-Knoll , Andrew Salch

We propose a definition of double categories whose composition of 1-cells is weak in both directions. Namely, a doubly weak double category is a double computad -- a structure with 2-cells of all possible double-categorical shapes --…

Category Theory · Mathematics 2026-05-25 Aaron David Fairbanks , Michael Shulman

We prove descent theorems for semiorthogonal decompositions using techniques from derived algebraic geometry. Our methods allow us to capture more general filtrations of derived categories and even marked filtrations, where one descends not…

Algebraic Geometry · Mathematics 2021-01-12 Benjamin Antieau , Elden Elmanto

We study simple extensions of pointed finite tensor categories, that is, tensor categories $\mathcal{C}$ admitting an abelian decomposition $\mathcal{C} \cong \mathcal{D} \oplus \mathcal{M}$ where $\mathcal{D}$ is a pointed tensor…

Category Theory · Mathematics 2026-03-06 Daniel Sebbag

We prove that an iterated function system of similarities on $\mathbb{R}$ that satisfies the weak separation condition and has an interval as its self-similar set satisfies the stronger generalized finite type condition. It is unknown if…

Dynamical Systems · Mathematics 2021-12-07 Kathryn E. Hare , Kevin G. Hare , Alex Rutar

Let $R$ be a commutative ring with unit. We consider the homotopy theory of the category of spectral sequences of $R$-modules with the class of weak equivalences given by those morphisms inducing a quasi-isomorphism at a certain fixed page.…

Algebraic Topology · Mathematics 2023-02-22 Muriel Livernet , Sarah Whitehouse

We continue our study of semi-strict tricategories in which the only weakness is in vertical composition. We assemble the doubly-degenerate such tricategories into a 2-category, defining weak functors and transformations. We exhibit a…

Category Theory · Mathematics 2023-08-22 Eugenia Cheng , Alexander S. Corner

We study the question when a category of ind-objects is abelian. Our answer allows a further generalization of the notion of weakly Tannakian categories introduced by the author. As an application we show that, under suitable conditions,…

Algebraic Geometry · Mathematics 2019-02-20 Daniel Schäppi

A semisimple element $s$ of a connected reductive group $G$ is said {\it quasi-isolated} (respectively {\it isolated}) if $C_G(s)$ (respectively $C_G^0(s)$) is not contained in a Levi subgroup of a proper parabolic subgroup of $G$. We study…

Group Theory · Mathematics 2007-05-23 Cédric Bonnafé

A Quillen model structure is presented by an interacting pair of weak factorization systems. We prove that in the world of locally presentable categories, any weak factorization system with accessible functorial factorizations can be lifted…

Category Theory · Mathematics 2022-05-23 Richard Garner , Magdalena Kedziorek , Emily Riehl