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We determine all affinely homogeneous hypersurfaces S^3 in R^4 whose Hessian is (invariantly) of constant rank 2, including the simply transitive ones. We find 34 inequivalent terminal branches yielding each to a nonempty moduli space of…

Differential Geometry · Mathematics 2024-04-30 Julien Heyd , Joel Merker

We classify all real hypersurfaces with three distinct constant principal curvatures in complex hyperbolic spaces of dimension greater than two.

Differential Geometry · Mathematics 2007-05-23 Jurgen Berndt , Jose Carlos Diaz-Ramos

We classify isoparametric hypersurfaces in complex hyperbolic spaces.

Differential Geometry · Mathematics 2017-06-13 Jose Carlos Diaz-Ramos , Miguel Dominguez-Vazquez , Victor Sanmartin-Lopez

In this paper, we classify hypersurfaces with constant principal curvatures in the four-dimensional Thurston geometry ${\rm Sol_0^4}$ under certain geometric conditions. As an application of the classification result, we give a complete…

Differential Geometry · Mathematics 2025-11-03 Marie D'haene , Guoxin Wei , Zeke Yao , Xi Zhang

Hypersurfaces are studied and classified under multiple additional assumptions in any Riemannian homogeneous space $(\mathbb{C}P^3, g_a)$, including nearly K\"ahler $\mathbb{C}P^3$. Notably, all extrinsically homogeneous hypersurfaces are…

Differential Geometry · Mathematics 2025-03-13 Michaël Liefsoens

We present simple examples of finite-dimensional connected homogeneous spaces (they are actually topological manifolds) with nonhomogeneous and nonrigid factors. In particular, we give an elementary solution of an old problem in general…

Geometric Topology · Mathematics 2012-03-21 M. Cárdenas , F. F. Lasheras , A. Quintero , D. Repovš

We prove that the complex of proper non-trivial non-degenerate subspaces of a finite-dimensional vector space endowed with a non-degenerate sesquilinear form is homotopy equivalent to a wedge of spheres. Additionally, we show that the same…

Combinatorics · Mathematics 2015-03-27 Alice Devillers , Ralf Köhl , Bernhard Muhlherr

We construct inhomogeneous isoparametric families of hypersurfaces with non-austere focal set on each symmetric space of non-compact type and rank greater than or equal to 3. If the rank is greater than or equal to 4, there are infinitely…

Differential Geometry · Mathematics 2023-09-19 Miguel Dominguez-Vazquez , Victor Sanmartin-Lopez

We classify real hypersurfaces in complex space forms with constant principal curvatures and whose Hopf vector field has two nontrivial projections onto the principal curvature spaces. In complex projective spaces such real hypersurfaces do…

Differential Geometry · Mathematics 2009-11-19 Jose Carlos Diaz-Ramos , Miguel Dominguez-Vazquez

We study various classes of real hypersurfaces that are not embeddable into more special hypersurfaces in higher dimension, such as spheres, real algebraic compact strongly pseudoconvex hypersurfaces or compact pseudoconvex hypersurfaces of…

Complex Variables · Mathematics 2015-02-16 Xiaojun Huang , Dmitri Zaitsev

We classify all real hypersurfaces with constant principal curvatures in the complex hyperbolic plane.

Differential Geometry · Mathematics 2007-05-23 Jurgen Berndt , Jose Carlos Diaz-Ramos

Motivated by problems arising in the complex analysis of perturbative quantum field theory, we investigate the homology of finite unions of certain non-degenerate quadratic affine hypersurfaces of complex dimension $n$ in general position.…

Mathematical Physics · Physics 2022-11-15 Maximilian Mühlbauer

We describe the subgroup of the mapping class group of a hypersurface in $\mathbb{CP}^4$ consisting of those diffeomorphisms which can be realised by monodromy.

Algebraic Topology · Mathematics 2025-01-22 Oscar Randal-Williams

This paper reproduces the text of a part of the Author's DPhil thesis. It gives a proof of the classification of non-trivial, finite homogeneous geometries of sufficiently high dimension which does not depend on the classification of the…

Group Theory · Mathematics 2017-01-19 David M. Evans

The automorphisms of all 4-dimensional, real Lie Algebras are presented in a comprehensive way. Their action on the space of $4\times 4$, real, symmetric and positive definite, matrices, defines equivalence classes which are used for the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 T. Christodoulakis , G. O. Papadopoulos , A. Dimakis

We construct an infinite family of homologous, non-isotopic, symplectic surfaces of any genus greater than one in a certain class of closed, simply connected, symplectic four-manifolds. Our construction is the first example of this…

Geometric Topology · Mathematics 2018-12-24 B. Doug Park , Mainak Poddar , Stefano Vidussi

The Russell cubic is a smooth contractible affine complex threefold which is not isomorphic to affine three-space. In previous articles, we discussed the structure of the automorphism group of this variety. Here we review some consequences…

Algebraic Geometry · Mathematics 2013-10-01 Adrien Dubouloz , Lucy Moser-Jauslin , Pierre-Marie Poloni

The classification work [5], [9] left unsettled only those anomalous isoparametric hypersurfaces with four principal curvatures and multiplicity pair $\{4,5\},\{6,9\}$ or $\{7,8\}$ in the sphere. By systematically exploring the ideal theory…

Differential Geometry · Mathematics 2011-05-23 Quo-Shin Chi

Hyperelliptic manifolds are natural generalizations of hyperelliptic surfaces in dimensions. We provide a full classification of the groups, which arise as the holonomy group of a 4-dimensional hyperelliptic manifold. The classification is…

Algebraic Geometry · Mathematics 2022-11-16 Andreas Demleitner

In this paper, we study hypersurfaces in $\mathbb{H}^2\times\mathbb{H}^2$. We first classify the hypersurfaces with constant principal curvatures and constant product angle function. Then, we classify homogeneous hypersurfaces and…

Differential Geometry · Mathematics 2023-03-17 Dong Gao , Hui Ma , Zeke Yao