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We classify six-dimensional homogeneous nearly K\"{a}hler manifolds and give a positive answer to Gray and Wolf's conjecture: every homogeneous nearly K\"{a}hler manifold is a Riemannian 3-symmetric space equipped with its canonical almost…

Differential Geometry · Mathematics 2007-05-23 Jean-Baptiste Butruille

We compute the spectra of the adjacency matrices of the semi-regular polytopes. A few different techniques are employed: the most sophisticated, which relates the 1-skeleton of the polytope to a Cayley graph, is based on methods akin to…

Combinatorics · Mathematics 2007-05-23 Nicolau C. Saldanha , Carlos Tomei

Using a special metric in the space of sequences, we give a geometric description of almost periodic sets in the $k$-dimensional Euclidean space. We prove the completeness of the space of almost periodic sets and some analogue of the…

Metric Geometry · Mathematics 2010-02-02 S. Favorov , Ye. Kolbasina

We discuss some finite homogeneous structures, addressing the question of universality of their automorphism groups. We also study the existence of so-called Kat\v{e}tov functors in finite categories of embeddings or homomorphisms.

Logic · Mathematics 2020-04-29 Wiesław Kubiś , Boriša Kuzeljević

In this article we classify totally geodesic submanifolds of homogeneous nearly K\"ahler 6-manifolds, and of the G2-cones over these 6-manifolds. To this end, we develop new techniques for the study of totally geodesic submanifolds of…

Differential Geometry · Mathematics 2025-06-10 Juan Manuel Lorenzo-Naveiro , Alberto Rodríguez-Vázquez

We define naturally Hermite-Lorentz metrics on almost-complex manifolds as special case of pseudo-Riemannian metrics compatible with the almost complex structure. We study their isometry groups.

Differential Geometry · Mathematics 2017-01-03 Ali Ben-Ahmed , Abdelghani Zeghib

In this article we classify totally geodesic submanifolds in arbitrary products of rank one symmetric spaces. Furthermore, we give infinitely many examples of irreducible totally geodesic submanifolds in Hermitian symmetric spaces with…

Differential Geometry · Mathematics 2024-06-06 A. Rodríguez-Vázquez

A perfect prismatoid is a convex polytope $P$ such that for every its facet $F$ the set $vert(P) \setminus vert(F)$ belongs to a supporting hyperplane $\alpha \parallel F$. We prove that every perfect prismatoid is affinely equivalent to…

Metric Geometry · Mathematics 2014-06-02 Marina Kozachok , Alexander Magazinov

We determine all four-dimensional homogeneous semi-symmetric neutral manifolds.

Differential Geometry · Mathematics 2022-02-25 Abderrazzak Benroummane

Let G be a complex reductive algebraic group. We study complete intersections in a spherical homogeneous space G/H defined by a generic collection of sections from G-invariant linear systems. Whenever nonempty, all such complete…

Algebraic Geometry · Mathematics 2015-06-11 Kiumars Kaveh , A. G. Khovanskii

We present the results of an investigation into the representations of Archimedean polyhedra (those polyhedra containing only one type of vertex figure) as quotients of regular abstract polytopes. Two methods of generating these…

Combinatorics · Mathematics 2009-10-14 Michael Hartley , Gordon Williams

This thesis is concerned with equidistant foliations of Euclidean space, i.e. partitions into complete, connected, properly embedded smooth submanifolds. The space of leaves is an Alexandrov space of nonnegative curvature and the canonical…

Differential Geometry · Mathematics 2007-12-04 Christian Boltner

We characterise simply-connected biquotients which potentially admit metrics of holonomy G_2. We prove that there are at most three real homotopy types of rationally elliptic such manifolds---all of them being formal. In the course of this…

Differential Geometry · Mathematics 2014-03-07 Manuel Amann

In this paper, we obtain the complete classification for compact hyperbolic Coxeter four-dimensional polytopes with eight facets.

Geometric Topology · Mathematics 2022-11-23 Jiming Ma , Fangting Zheng

Urysohn constructed a separable complete universal metric space homogeneous for all finite subspaces, which is today called the Urysohn universal metric space. Some authors have recently investigated an ultrametric analogue of this space.…

Metric Geometry · Mathematics 2023-06-27 Yoshito Ishiki

Symmetric Grothendieck polynomials are inhomogeneous versions of Schur polynomials that arise in combinatorial $K$-theory. A polynomial has saturated Newton polytope (SNP) if every lattice point in the polytope is an exponent vector. We…

Combinatorics · Mathematics 2017-10-17 Laura Escobar , Alexander Yong

This work presents the tessellations and polytopes from the perspective of both n-dimensional geometry and abstract symmetry groups. It starts with a brief introduction to the terminology and a short motivation. In the first part, it…

Group Theory · Mathematics 2023-01-06 Plamen Dimitrov

We consider real isotropic geodesics on manifolds endowed with a pseudoconformal structure and their applications to the theory of lightlike hypersurfaces on such manifolds, the geometry of four-dimensional conformal structures of…

Differential Geometry · Mathematics 2007-05-23 Maks A. Akivis , Vladislav V. Goldberg

The goal of this article is to investigate nontrivial $m$-quasi-Einstein manifolds globally conformal to an $n$-dimensional Euclidean space. By considering such manifolds, whose conformal factors and potential functions are invariant under…

Differential Geometry · Mathematics 2019-12-09 Ernani Ribeiro , Keti Tenenblat

The Wythoff construction takes a $d$-dimensional polytope $P$, a subset $S$ of $\{0,..., d\}$ and returns another $d$-dimensional polytope $P(S)$. If $P$ is a regular polytope, then $P(S)$ is vertex-transitive. This construction builds a…

Combinatorics · Mathematics 2008-08-11 Michel Deza , Mathieu Dutour , Sergey Shpectorov
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