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It is shown that the first order (Palatini) variational principle for a generic nonlinear metric-affine Lagrangian depending on the (symmetrized) Ricci square invariant leads to an almost-product Einstein structure or to an almost-complex…

dg-ga · Mathematics 2011-07-19 A. Borowiec , M. Ferraris , M. Francaviglia , I. Volovich

Connections with (skew-symmetric) torsion on non-symmetric Riemannian manifold satisfying the Einstein metricity condition (NGT with torsion) are considered. It is shown that an almost Hermitian manifold is an NGT with torsion if and only…

Differential Geometry · Mathematics 2016-03-23 Stefan Ivanov , Milan Zlatanovic

We study a version of Calder\'on's problem for harmonic maps between Riemannian manifolds. By using the higher linearization method, we first show that the Dirichlet-to-Neumann map determines the metric on the domain up to a natural gauge…

Analysis of PDEs · Mathematics 2024-11-05 Sebastián Muñoz-Thon

Given a branched cover of manifolds, one can lift homeomorphisms along the cover to obtain a (virtual) homomorphism between mapping class groups. Following a question of Margalit-Winarski, we study the injectivity of this lifting map in the…

Geometric Topology · Mathematics 2025-03-11 Trent Lucas

The reproducing kernel Hilbert space (RKHS) embedding method is a recently introduced estimation approach that seeks to identify the unknown or uncertain function in the governing equations of a nonlinear set of ordinary differential…

Optimization and Control · Mathematics 2020-07-14 Jia Guo , Sai Tej Paruchuri , Andrew J. Kurdila

We discuss the possibility of extending different versions of the Campbell-Magaard theorem, which have already been established in the context of semi-Riemannian geometry, to the context of Weyl's geometry. We show that some of the known…

General Relativity and Quantum Cosmology · Physics 2017-01-31 R. Avalos , F. Dahia , C. Romero

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 the present work we use the Levelt's valuation theory to describe all monodromy representations that can be realized by Riemann equation. Also we show that if the monodromy of Riemann equation lies in $SL(2,\mathbb{C})$, then such a…

Classical Analysis and ODEs · Mathematics 2007-05-23 V. Poberezhny

In this note, we make two methodical observations. $\bullet$ We prove in a simple explicit way that a necessary and sufficient condition for a K\"ahler manifold to be hyperk\"ahler is $h_{i\bar k} h_{j\bar l } \Omega^{\bar k \bar l} \ =\ C…

Differential Geometry · Mathematics 2026-03-31 A. V. Smilga

We say that a cover of surfaces S -> X has the Birman--Hilden property if the subgroup of the mapping class group of X consisting of mapping classes that have representatives that lift to S embeds in the mapping class group of S modulo the…

Geometric Topology · Mathematics 2013-09-17 Rebecca R. Winarski

This thesis delves into the geometry of abstract tropical curves, exploring their complete linear system and associated tropical submodules. We establish a lower bound on the dimension of tropical submodules in terms of the Baker-Norine…

Algebraic Geometry · Mathematics 2025-06-27 Matthew Dupraz

In this paper, we are concerned with the Neumann problem for a class of quasilinear stationary Kirchhoff-type potential systems, which involves general variable exponents elliptic operators with critical growth and real positive parameter.…

Analysis of PDEs · Mathematics 2023-03-06 Nabil Chems Eddine , Dušan D. Repovš

Given a finite collection of $C^1$ complex vector fields on a $C^2$ manifold $M$ such that they and their complex conjugates span the complexified tangent space at every point, the classical Newlander-Nirenberg theorem gives conditions on…

Complex Variables · Mathematics 2020-04-13 Brian Street

We develop a new purely combinatorial approach to N. Steenrod's problem on realisation of cycles. We prove that every n-dimensional homology class of every topological space can be realised with some multiplicity by an image of a…

Algebraic Topology · Mathematics 2024-11-20 Alexander A. Gaifullin

An integrable generalization of the super Kaup-Newell(KN) isospectral problem is introduced and its corresponding generalized super KN soliton hierarchy are established based on a Lie super-algebra B(0,1) and super-trace identity in this…

Exactly Solvable and Integrable Systems · Physics 2017-06-14 Beibei Hu , Tiecheng Xia , Ling Zhang

In this paper, we use normal surface theory to study Dehn filling on a knot-manifold. First, it is shown that there is a finite computable set of slopes on the boundary of a knot-manifold that bound normal and almost normal surfaces in a…

Geometric Topology · Mathematics 2007-05-23 William Jaco , Eric Sedgwick

The Milnor Problem (modified) in the theory of group growth asks whether any finite presented group of vanishing algebraic entropy has at most polynomial growth. We show that a positive answer to the Milnor Problem (modified) is equivalent…

Differential Geometry · Mathematics 2023-05-16 Lina Chen , Xiaochun Rong , Shicheng Xu

In recent developments, a general approach for solving Riemann--Hilbert problems numerically has been developed. We review this numerical framework, and apply it to the calculation of orthogonal polynomials on the real line. Combining this…

Mathematical Physics · Physics 2012-10-09 Sheehan Olver , Thomas Trogdon

It is proved that any (repetitive) Riemannian manifold of bounded geometry can be realized as a leaf of some (minimal) Riemannian matchbox manifold without holonomy. Our methods can be adapted to achieve Cantor transversals or a prescribed…

Geometric Topology · Mathematics 2024-12-17 Jesús A. Álvarez López , Ramón Barral Lijó

We consider non-Kaehler compact complex manifolds which are homogeneous under the action of a compact Lie group of biholomorphisms and we investigate the existence of special (invariant) Hermitian metrics on these spaces. We focus on a…

Differential Geometry · Mathematics 2016-08-30 Fabio Podestà