Four-dimensional ball-homogeneous and -spaces.
Calvaruso, G., Tondeur, Ph., Vanhecke, Lieven (1997)
Beiträge zur Algebra und Geometrie
Kouei Sekigawa, Hiroshi Suga, Lieven Vanhecke (1992)
Commentationes Mathematicae Universitatis Carolinae
We prove that a four-dimensional, connected, simply connected and complete Riemannian manifold which is curvature homogeneous up to order two is a homogeneous Riemannian space.
Paul Baird, Jade Ventura (2021)
Archivum Mathematicum
Biconformal deformations take place in the presence of a conformal foliation, deforming by different factors tangent to and orthogonal to the foliation. Four-manifolds endowed with a conformal foliation by surfaces present a natural context to put into effect this process. We develop the tools to calculate the transformation of the Ricci curvature under such deformations and apply our method to construct Einstein -manifolds. Examples of one particular family have ends which collapse asymptotically...
K. Gawędzki (1976)
M. Brin, H. Karcher (1984)
Compositio Mathematica
Frédéric Bourgeois, Alexandru Oancea (2010)
Journal of the European Mathematical Society
We study the parametrized Hamiltonian action functional for finite-dimensional families of Hamiltonians. We show that the linearized operator for the -gradient lines is Fredholm and surjective, for a generic choice of Hamiltonian and almost complex structure. We also establish the Fredholm property and transversality for generic -invariant families of Hamiltonians and almost complex structures, parametrized by odd-dimensional spheres. This is a foundational result used to define -equivariant...
Yong-Geun Oh (1996)
Mathematische Zeitschrift
Gerd Schmalz, Jan Slovák (2012)
Open Mathematics
There are only some exceptional CR dimensions and codimensions such that the geometries enjoy a discrete classification of the pointwise types of the homogeneous models. The cases of CR dimensions n and codimensions n 2 are among the very few possibilities of the so-called parabolic geometries. Indeed, the homogeneous model turns out to be PSU(n+1,n)/P with a suitable parabolic subgroup P. We study the geometric properties of such real (2n+n 2)-dimensional submanifolds in for all n > 1. In...
Pripoae, Cristina-Liliana, Pripoae, Gabriel-Teodor (2009)
Balkan Journal of Geometry and its Applications (BJGA)
Markl, Martin (2003)
Proceedings of the 22nd Winter School "Geometry and Physics"
It is well-known that a based space is of the weak homotopy type of a loop space iff it is a grouplike algebra over an -operad. The classical model for such an operad consists of Stasheff’s associahedra. The present paper describes a similar recognition principle for free loop spaces. Let be an operad, a -module and a -algebra. An -trace over consists of a space and a module homomorphism over the operad homomorphism given by the algebra structure on . Let be the little 1-cubes...
Irena Čomić (1991)
Publications de l'Institut Mathématique
Bölcskei, Attila, Szilágyi, Brigitta (2007)
Beiträge zur Algebra und Geometrie
Bar-Natan, Dror (2000)
Proceedings of the 19th Winter School "Geometry and Physics"
Summary of the three lectures. These notes are available electronically at http://www.ma.huji.ac.il/~drorbn/Talks/Srni-9901/notes.html.
Mircea Neagu (2006)
Archivum Mathematicum
The aim of this paper is to construct a canonical nonlinear connection on the 1-jet space from the Euler-Lagrange equations of the quadratic multi-time Lagrangian function
Andrée Charles Ehresmann (1984)
Cahiers de Topologie et Géométrie Différentielle Catégoriques
Pişcoran, Laurian (2004)
General Mathematics
Neagu, Mircea (2007)
Novi Sad Journal of Mathematics
Sergey E. Stepanov, Irina I. Tsyganok, Josef Mikeš (2013)
Mathematica Bohemica
The concept of the Ricci soliton was introduced by R. S. Hamilton. The Ricci soliton is defined by a vector field and it is a natural generalization of the Einstein metric. We have shown earlier that the vector field of the Ricci soliton is an infinitesimal harmonic transformation. In our paper, we survey Ricci solitons geometry as an application of the theory of infinitesimal harmonic transformations.
Yoshiyuki Watanabe, Hiroshi Mori (1998)
Archivum Mathematicum
We construct a family of almost quaternionic Hermitian structures from an almost contact metric 3-structure and also do three kinds of quaternionic Kähler structures from a Sasakian 3-structure. In particular we have a generalization of the second main result of Boyer-Galicki-Mann [5].
Călin, Constantin, Crasmareanu, Mircea (2010)
Bulletin of the Malaysian Mathematical Sciences Society. Second Series