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We solve the problem of reducing to the simplest and convenient for our purposes, canonical form for an arbitrary pair of compatible nonlocal Poisson brackets of hydrodynamic type generated by metrics of constant Riemannian curvature in…

Differential Geometry · Mathematics 2010-01-04 O. I. Mokhov

We consider a pair of smooth manifolds, which are the counterparts in the even-dimensional and odd-dimensional cases. They are separately an almost complex manifold with Norden metric and an almost contact manifolds with B-metric,…

Differential Geometry · Mathematics 2015-05-06 Mancho Manev

On H-type sub-Riemannian manifolds we establish sub-Hessian and sub-Laplacian comparison theorems which are uniform for a family of approximating Riemannian metrics converging to the sub-Riemannian one. We also prove a sharp sub-Riemannian…

Differential Geometry · Mathematics 2025-05-06 Fabrice Baudoin , Erlend Grong , Luca Rizzi , Sylvie Vega-Molino

We define compatibility between Jacobi structures and pseudo-Riemannian cometrics on Jacobi algebroids. This notion is a generalization of the compatibility between Poisson structures and pseudo-Riemannian cometrics on manifolds, which was…

Symplectic Geometry · Mathematics 2023-09-12 Naoki Kimura , Tomoya Nakamura

Almost para-Hermitian manifold it is manifold equipped with almost para-complex structure and compatible pseudo-metric of neutral signature. It is considered a class of immersions of almost para-Hermitian manifolds into almost…

Differential Geometry · Mathematics 2017-10-27 Piotr Dacko

Any multiplicative quiver variety is endowed with a Poisson structure constructed by Van den Bergh through reduction from a Hamiltonian quasi-Poisson structure. The smooth locus carries a corresponding symplectic form defined by Yamakawa…

Symplectic Geometry · Mathematics 2026-05-08 Maxime Fairon

We characterize general pseudo-harmonic morphisms from a Riemannian manifold to a Hermitian manifold as pseudo horizontally weakly conformal maps with an additional property. We study to what extent we can (locally) describe these…

Differential Geometry · Mathematics 2007-12-18 Radu Slobodeanu

We discuss pseudo-Riemannian metrics on 2-dimensional manifolds such that the geodesic flow admits a nontrivial integral quadratic in velocities. We construct local normal forms of such metrics. We show that these metrics have certain…

Mathematical Physics · Physics 2015-05-13 Alexey V. Bolsinov , Vladimir S. Matveev , Giuseppe Pucacco

We introduce the notions of h-conformal slant submersions and almost h-conformal slant submersions from almost quaternionic Hermitian manifolds onto Riemannian manifolds as a generalization of Riemannian submersions, horizontally conformal…

Differential Geometry · Mathematics 2018-08-21 Kwang Soon Park , JeongHyeong Park

We study all four-dimensional simply-connected indecomposable non-semisimple pseudo-Riemannian symmetric spaces whose metric has signature (2,2). We present models and compute their isometry groups. We solve the problem of the existence or…

Differential Geometry · Mathematics 2024-05-02 Ines Kath , Matti Lyko

We consider a generalization of Riemannian geometry that naturally arises in the framework of control theory. Let $X$ and $Y$ be two smooth vector fields on a two-dimensional manifold $M$. If $X$ and $Y$ are everywhere linearly independent,…

Optimization and Control · Mathematics 2007-05-23 Andrei A. Agrachev , Ugo Boscain , Mario Sigalotti

The question whether a Riemannian manifold is geodesically connected can be studied from geometrical as well as variational methods, and accurate results can be obtained by using the associated distance and related properties of the…

Differential Geometry · Mathematics 2023-04-21 Miguel Sanchez

We provide an axiomatic approach to the theory of local tangent cones of regular sub-Riemannian manifolds and the differentiability of mappings between such spaces. This axiomatic approach relies on a notion of a dilation structure which is…

Metric Geometry · Mathematics 2010-09-09 Svetlana Selivanova , Sergey Vodopyanov

Two pseudo-Riemannian metrics are called projectively equivalent if their unparametrized geodesics coincide. The degree of mobility of a metric is the dimension of the space of metrics that are projectively equivalent to it. We give a…

Differential Geometry · Mathematics 2017-11-28 Vladimir S. Matveev , Stefan Rosemann

The purpose of this paper is to explore conditions which guarantee Lipschitz-continuity of harmonic maps w.r.t. quasihyperbolic metrics. For instance, we prove that harmonic quasiconformal maps are Lipschitz w.r.t. quasihyperbolic metrics.

Complex Variables · Mathematics 2010-04-12 Miodrag Mateljević , Matti Vuorinen

As a generalization of Riemannian submersions, horizontally conformal submersions, semi-invariant submersions, h-semi-invariant submersions, almost h-semi-invariant submersions, conformal semi-invariant submersions, we introduce h-conformal…

Differential Geometry · Mathematics 2017-08-28 Kwang-Soon Park

We prove the equivalence of several natural notions of conformal maps between sub-Riemannian manifolds. Our main contribution is in the setting of those manifolds that support a suitable regularity theory for subelliptic $p$-Laplacian…

Analysis of PDEs · Mathematics 2017-01-06 Luca Capogna , Giovanna Citti , Enrico Le Donne , Alessandro Ottazzi

Pseudo-harmonic morphisms give rise on the domain space to a distribution which admits an almost complex structure compatible with the given Riemannian metric. We shall show that this property, together with the harmonicity, are preserved…

Differential Geometry · Mathematics 2007-05-23 Radu Slobodeanu

We classify all smooth flat Riemannian metrics on the two-dimensional plane. In the complete case, it is well-known that these metrics are isometric to the Euclidean metric. In the incomplete case, there is an abundance of…

Differential Geometry · Mathematics 2020-01-14 Vincent E. Coll, , Lee B. Whitt

We present a variation of quasi-isometry to approach the problem of defining a geometric notion equivalent to commensurability. In short, this variation can be summarized as "quasi-isometry with uniform parameters for a large enough family…

Group Theory · Mathematics 2010-06-01 Andreas Lochmann