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The main purpose of this work is the study of the homotopy theory of dg-categories up to quasi-equivalences. Our main result provides a natural description of the mapping spaces between two dg-categories $C$ and $D$ in terms of the nerve of…

Algebraic Geometry · Mathematics 2007-05-23 B. Toen

In Part 1, we describe six projective-type model structures on the category of differential graded modules over a differential graded algebra A over a commutative ring R. When R is a field, the six collapse to three and are well-known, at…

Category Theory · Mathematics 2014-12-03 Tobias Barthel , J. P. May , Emily Riehl

The classical construction of the symplectic structure on the space of geodesic trajectories via Hamiltonian reduction fails in the pseudo-Riemannian setting due to a dimensional mismatch created by the null geodesics. This paper proposes a…

Differential Geometry · Mathematics 2025-10-08 Patrick Iglesias-Zemmour

We associate to a quiver and a subquiver $(Q,F)$ a stopped Weinstein manifold $X$ whose Legendrian attaching link is a singular Legendrian unknot link $\varLambda$. We prove that the relative Ginzburg algebra of $(Q,F)$ is quasi-isomorphic…

Symplectic Geometry · Mathematics 2025-10-15 Johan Asplund

Working in the Arone-Ching framework for homotopical descent, it follows that the Bousfield-Kan completion map with respect to integral homology is the unit of a derived adjunction. We prove that this derived adjunction, comparing spaces…

Algebraic Topology · Mathematics 2018-10-16 Jacobson R. Blomquist , John E. Harper

The category of unital (unbounded) dg cocommutative coalgebras over a field of characteristic zero is provided with a structure of simplicial closed model category. This generalizes the model structure defined by Quillen in 1969 for…

Algebraic Geometry · Mathematics 2007-05-23 V. Hinich

Given a bundle of chain complexes, the algebra of functions on its shifted cotangent bundle has a natural structure of a shifted Poisson algebra. We show that if two such bundles are homotopy equivalent, the corresponding Poisson algebras…

Differential Geometry · Mathematics 2019-04-04 Ricardo Campos

The normalized cochain complex of a simplicial set N^*(Y) is endowed with the structure of an E_{infinity} algebra. More specifically, we prove in a previous article that N^*(Y) is an algebra over the Barratt-Eccles operad. According to M.…

Algebraic Topology · Mathematics 2007-05-23 Benoit Fresse

The double cobar construction of a double suspension comes with a Connes-Moscovici structure, that is a homotopy G-algebra (or Gerstenhaber-Voronov algebra) structure together with a particular BV-operator up to a homotopy. We show that the…

Algebraic Topology · Mathematics 2014-06-23 Alexandre Quesney

We provide examples of inductive fibrant replacements in fibrantly generated model categories constructed as Postnikov towers. These provide new types of arguments to compute homotopy limits in model categories. We provide examples for…

Algebraic Topology · Mathematics 2024-04-09 Maximilien Péroux

Cheeger-Simons differential characters, Deligne cohomology in the smooth category, the Hopkins-Singer construction of ordinary differential cohomology and the recent Harvey-Lawson constructions are each in two distinct ways Abelian group…

Algebraic Topology · Mathematics 2014-02-26 James Simons , Dennis Sullivan

We introduce a graph-theoretic condition, called $(n,m)$--branching, that ensures a combinatorial round tree with controlled branching parameters can be quasi-isometrically embedded in the Davis complex of the right-angled Coxeter group…

Group Theory · Mathematics 2025-10-07 Christopher H. Cashen , Pallavi Dani , Kevin Schreve , Emily Stark

We show a first rectification result for homotopy chain coalgebras over a field. On the one hand, we consider the $\infty$-category obtained by localizing differential graded coalgebras over an operad with respect to quasi-isomorphisms; on…

Algebraic Topology · Mathematics 2026-04-21 Dan Petersen , Victor Roca i Lucio , Sinan Yalin

It has been discussed earlier that ( weak quasi-) quantum groups allow for conventional interpretation as internal symmetries in local quantum theory. From general arguments and explicit examples their consistency with (braid-) statistics…

High Energy Physics - Theory · Physics 2009-10-28 Volker Schomerus

We consider a countably generated and uniformly closed algebra of bounded functions. We assume that there is a lower semicontinuous, with respect to the supremum norm, quadratic form and that normal contractions operate in a certain sense.…

Functional Analysis · Mathematics 2018-06-29 Michael Hinz , Alexander Teplyaev

Wright showed that, if a 1-ended simply connected locally compact ANR Y with pro-monomorphic fundamental group at infinity admits a proper Z-action, then that fundamental group at infinity can be represented by an inverse sequence of…

Geometric Topology · Mathematics 2020-04-29 Ross Geoghegan , Craig Guilbault , Michael Mihalik

Let $\Sigma$ be a fan inside the lattice $\mathbb{Z}^n$, and $\mathcal{E}:\mathbb{Z}^n \rightarrow \operatorname{Pic}{S}$ be a map of abelian groups. We introduce the notion of a principal toric fibration $\mathcal{X}_{\Sigma, \mathcal{E}}$…

Algebraic Geometry · Mathematics 2023-04-04 Yuxuan Hu , Pyongwon Suh

In this paper we show that it is possible to define a topology on the category of formal schemes over a ring of $p$-adic integers such that the left adjoint of the Greenberg Transform is a site cocontinuous functor when we equip the…

Algebraic Geometry · Mathematics 2019-10-02 Geoff Vooys

Working in the context of symmetric spectra, we consider any higher algebraic structures that can be described as algebras over an operad O. We prove that the fundamental adjunction comparing O-algebra spectra with coalgebra spectra over…

Algebraic Topology · Mathematics 2015-07-24 Michael Ching , John E. Harper

Given a simplicial group G, there are two known classifying simplicial set constructions, the Kan classifying simplicial set Wbar G and Diag N G, where N denotes the dimensionwise nerve. They are known to be weakly homotopy equivalent. We…

Algebraic Topology · Mathematics 2011-03-31 Sebastian Thomas