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We show that hyperplane sections of strongly formal manifolds inherit strong formality. In particular, this property holds for generalized complete intersections defined by positive line bundles with trivial first de Rham cohomology group.…

Differential Geometry · Mathematics 2026-04-15 Lapo Rubini

A Theorem of Wang in [Wa] implies that any holomorphic parallelism on a compact complex manifold M is flat with respect to some complex Lie algebra structure whose dimension coincides with that of M. We study here rational parallelisms on…

Differential Geometry · Mathematics 2019-12-23 Indranil Biswas , Sorin Dumitrescu

It is noted that the higher version of M. Kontsevich's Formality Theorem is much easier than the original one. Namely, we prove that the higher Hochschild-Kostant-Rosenberg map is already a homotopy e_{n+1}-formality quasi-isomorphism…

Quantum Algebra · Mathematics 2016-01-21 Damien Calaque , Thomas Willwacher

Let $X$ be a finite CW complex and let $h_1, h_2: C(X)\to A$ be two unital \hm s, where $A$ is a unital C*-algebra. We study the problem when $h_1$ and $h_2$ are approximately homotopic. We present a $K$-theoretical necessary and sufficient…

Operator Algebras · Mathematics 2008-01-28 Huaxin Lin

We prove a "purity implies formality" statement in the context of the rational homotopy theory of smooth complex algebraic varieties, and apply it to complements of hypersurface arrangements. In particular, we prove that the complement of a…

Algebraic Geometry · Mathematics 2016-10-05 Clément Dupont

We show that Willwacher's cyclic formality theorem can be extended to preserve natural Gravity operations on cyclic multivector fields and cyclic multidifferential operators. We express this in terms of a homotopy Gravity quasi-isomorphism…

Quantum Algebra · Mathematics 2017-07-04 Ricardo Campos , Benjamin C. Ward

It is a conjecture of Koll\'ar that a variety $X$ with rational singularities in some open subvariety $U$ has a rationalification; that is, a proper, birational morphism $f: Y \rightarrow X$ such that $Y$ has rational singularities, and…

Algebraic Geometry · Mathematics 2015-03-24 Jeremy Berquist

We prove new structural results for the rational homotopy type of the classifying space $B\operatorname{aut}(X)$ of fibrations with fiber a simply connected finite CW-complex $X$. We first study nilpotent covers of $B\operatorname{aut}(X)$…

Algebraic Topology · Mathematics 2025-10-15 Alexander Berglund , Tomáš Zeman

In this paper we describe and continue the study begun by the author, Jones, and Segal, of the homotopy theory that underlies Floer theory. In that paper the authors addressed the question of realizing a Floer complex as the celluar chain…

Algebraic Topology · Mathematics 2008-02-21 Ralph L. Cohen

We introduce the notion of smooth cell complexes and its subclass consisting of gathered cell complexes within the category of diffeological spaces (cf. Definitions 1 and 3). It is shown that the following hold. (1) With respect to the…

Algebraic Topology · Mathematics 2019-12-12 Tadayuki Haraguchi , Kazuhisa Shimakawa

A hyperplane arrangement is called formal provided all linear dependencies among the defining forms of the hyperplanes are generated by ones corresponding to intersections of codimension two. The significance of this notion stems from the…

Combinatorics · Mathematics 2024-07-03 Tilman Möller , Paul Mücksch , Gerhard Roehrle

One proves that the category of globular CW-complexes up to dihomotopy is equivalent to the category of flows up to weak dihomotopy. This theorem generalizes the classical theorem which states that the category of CW-complexes up to…

Algebraic Topology · Mathematics 2021-08-25 Philippe Gaucher

We define the totally nonnegative matroid Schubert variety $\mathcal Y_V$ of a linear subspace $V \subset \mathbb R^n$. We show that $\mathcal Y_V$ is a regular CW complex homeomorphic to a closed ball, with strata indexed by pairs of…

Combinatorics · Mathematics 2023-10-31 Xuhua He , Connor Simpson , Kaitao Xie

We prove that if a finite group $G$ has a representation with fixity $f$, then it acts freely and homologically trivially on a finite CW-complex homotopy equivalent to a product of $f+1$ spheres. This shows, in particular, that every finite…

Algebraic Topology · Mathematics 2012-03-28 Ozgun Unlu , Ergun Yalcin

To a digraph with a choice of certain integral basis, we construct a CW complex, whose integral singular cohomology is canonically isomorphic to the path cohomology of the digraph as introduced in \cite{GLMY}. The homotopy type of the CW…

Combinatorics · Mathematics 2014-09-23 An Huang , Shing-Tung Yau

We consider certain rational homotopical conditions of simly connected CW complex $X$ such that the rational cohomology of the classifying space $Baut_1X$ for fibrations with two-stage fibre $X$ is (not) free. First, we consider when is…

Algebraic Topology · Mathematics 2015-04-28 Hirokazu Nishinobu , Toshihiro Yamaguchi

We show a Gottlieb element in the rational homotopy of a simply connected space $X$ implies a structural result for the Sullivan minimal model, with different results depending on parity. In the even-degree case, we prove a rational…

Algebraic Topology · Mathematics 2022-06-30 Gregory Lupton , Samuel Bruce Smith

We prove existence of extension dimension for paracompact spaces. Here is the main result of the paper: \proclaim{Theorem} Suppose X is a paracompact space. There is a CW complex K such that {a.} K is an absolute extensor of X up to…

General Topology · Mathematics 2008-02-27 Jerzy Dydak

The Kontsevich-Soibelman solution of the cyclic version of Deligne's conjecture and the formality of the operad of little discs on a cylinder provide us with a natural homotopy calculus structure on the pair (C^*(A), C_*(A)) ``Hochschild…

K-Theory and Homology · Mathematics 2008-08-01 Vasiliy Dolgushev , Dmitry Tamarkin , Boris Tsygan

Let $T$ be a compact torus. We prove that, up to equivariant rational equivalence, the category of $T$-simply connected, $T$-finite type $T$-spaces with finitely many isotropy types is completely described by certain finite systems of…

Algebraic Topology · Mathematics 2021-06-02 Leopold Zoller