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We present a new approach to simple homotopy theory of polyhedra using finite topological spaces. We define the concept of collapse of a finite space and prove that this new notion corresponds exactly to the concept of a simplicial…

Algebraic Topology · Mathematics 2007-05-23 Jonathan Ariel Barmak , Elias Gabriel Minian

We classify locally homogeneous quasi-Sasakian manifolds in dimension five that admit a parallel spinor $\psi$ of algebraic type $F \cdot \psi = 0$ with respect to the unique connection $\nabla$ preserving the quasi-Sasakian structure and…

Differential Geometry · Mathematics 2007-05-23 Thomas Friedrich , Stefan Ivanov

In this master thesis, we extend results from classical simple homotopy theory to the world of stratified homotopy theory. To obtain a well-established framework to work in, we prove a series of results on two model categories of simplicial…

Algebraic Topology · Mathematics 2021-02-16 Lukas Waas

In this paper, we introduce a bordism category $\mathcal{C}_d^{PL}$ whose objects are bundles of closed $(d-1)$-dimensional piecewise linear manifolds and whose morphisms are bundles of $d$-dimensional piecewise linear cobordisms. In the…

Geometric Topology · Mathematics 2025-09-24 Mauricio Gomez Lopez

In this expository note, recent results of Kishimoto and Matsushita on triangulated manifolds are linked to the classical criterion on the normal Stiefel-Whitney classes for existence of an embedding of a smooth closed manifold into…

Geometric Topology · Mathematics 2025-04-03 M. C. Crabb

In this thesis we define the notion of a locally stratified space. Locally stratified spaces are particular kinds of streams and d-spaces which are locally modelled on stratified spaces. We construct a locally presentable and cartesian…

Algebraic Topology · Mathematics 2020-04-06 Stefano Nicotra

Given a compact manifold $X$ with boundary and a submersion $f : X \rightarrow Y$ whose restriction to the boundary of $X$ has isolated critical points with distinct critical values and where $Y$ is $[0,1]$ or $S^1$, the connected…

Algebraic Topology · Mathematics 2020-06-23 Gunnar Carlsson , Benjamin Filippenko

For a fixed closed manifold $P$, we construct a cobordism category of embedded manifolds with a single Baas-Sullivan singularity of type $P$. Our main theorem identifies the homotopy type of the classifying space of this cobordism category…

Algebraic Topology · Mathematics 2014-12-15 Nathan Perlmutter

Implementing an idea due to John Baez and James Dolan we define new invariants of Whitney stratified manifolds by considering the homotopy theory of smooth transversal maps. To each Whitney stratified manifold we assign transversal homotopy…

Algebraic Topology · Mathematics 2009-10-20 Jonathan Woolf

Closure spaces are a generalisation of topological spaces obtained by removing the idempotence requirement on the closure operator. We adapt the standard notion of bisimilarity for topological models, namely Topo-bisimilarity, to closure…

Logic in Computer Science · Computer Science 2021-05-17 Vincenzo Ciancia , Diego Latella , Mieke Massink Erik de Vink

We construct a spectral sequence associated to a stratified space, which computes the compactly supported cohomology groups of an open stratum in terms of the compactly supported cohomology groups of closed strata and the reduced cohomology…

Algebraic Topology · Mathematics 2017-06-14 Dan Petersen

The goal of this article is to extend a theorem of Lurie \[ \mathsf{Sh}_A (X) = \mathsf{Fun}(\mathsf{Exit}_A (X), \mathsf{S}) \] representing constructible sheaves with values in $ \mathsf{S} $, the $ \infty $-category of spaces, on a…

Algebraic Topology · Mathematics 2021-02-25 Damien Lejay

A principal bundle over the connected sum of two manifolds need not be diffeomorphic or even homotopy equivalent to a non-trivial connected sum of manifolds. We show however that the homology of the total space of a bundle formed a pullback…

Algebraic Topology · Mathematics 2021-12-13 Lisa C Jeffrey , Paul Selick

By a theorem of Banagl-Chriestenson, intersection spaces of depth one pseudomanifolds exhibit generalized Poincar\'{e} duality of Betti numbers, provided that certain characteristic classes of the link bundles vanish. In this paper, we show…

Algebraic Topology · Mathematics 2019-04-09 Dominik Wrazidlo

Manifolds and fiber bundles, while superficially different, have strong parallels; in particular, they are both defined in terms of equivalence classes of atlases or in terms of maximal atlases, with the atlases treated as mere adjuncts.…

Algebraic Topology · Mathematics 2019-06-28 Seymour J. Metz

We construct persistent bundles over configuration spaces of hard spheres and use the characteristic classes of these persistent bundles to give obstructions for embedding problems. The configuration spaces of $k$-hard spheres ${\rm…

Algebraic Topology · Mathematics 2025-08-13 Shiquan Ren

By ECS manifolds one means pseudo-Riemannian manifolds of dimensions $\,n\ge4\,$ which have parallel Weyl tensor, but not for one of the two obvious reasons: conformal flatness or local symmetry. As shown by Roter [10, 2], they exist for…

Differential Geometry · Mathematics 2023-11-06 Andrzej Derdzinski

We introduce the notion of a relative spherical category. We prove that such a category gives rise to the generalized Kashaev and Turaev-Viro-type 3-manifold invariants defined in arXiv:1008.3103 and arXiv:0910.1624, respectively. In this…

Geometric Topology · Mathematics 2014-10-01 Nathan Geer , Bertrand Patureau-Mirand

We prove that closed manifolds admitting a generic metric whose sectional curvature is locally quasi-constant are graphs of space forms. In the more general setting of QC spaces where sets of isotropic points are arbitrary, under suitable…

Differential Geometry · Mathematics 2020-04-08 Louis Funar

Closure spaces, a generalisation of topological spaces, have shown to be a convenient theoretical framework for spatial model checking. The closure operator of closure spaces and quasi-discrete closure spaces induces a notion of…

Logic in Computer Science · Computer Science 2025-09-03 Vincenzo Ciancia , Diego Latella , Mieke Massink , Erik P. de Vink