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We introduce the notions of the caustic-equivalence and the weak caustic-equivalence relations of reticular Lagrangian maps in order to give a generic classification of caustics on a corner. We give the figures of all generic caustics on a…

Differential Geometry · Mathematics 2011-10-18 Takaharu Tsukada

We characterize isometric actions on compact Kaehler manifolds admitting a Lagrangian orbit, describing under which condition the Lagrangian orbit is unique. We furthermore give the complete classification of simple groups acting on the…

Differential Geometry · Mathematics 2008-07-18 Lucio Bedulli , Anna Gori

Euler used intrinsic equations expressing the radius of curvature as a function of the angle of inclination to find curves similar to their evolutes. We interpret the evolute of a plane curve optically, as the caustic (envelope) of light…

Differential Geometry · Mathematics 2022-06-22 Sergiy Koshkin , Ivan Rocha

In a cold-dark-matter universe, cosmological structure formation proceeds in rough analogy to origami folding. Dark matter occupies a three-dimensional 'sheet' of free- fall observers, non-intersecting in six-dimensional velocity-position…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-17 Mark C. Neyrinck

The space ${\Bbb{L}}$ of oriented lines, or rays, in ${\Bbb{R}}^3$ is a 4-dimensional space with an abundance of natural geometric structure. In particular, it boasts a neutral K\"ahler metric which is closely related to the Euclidean…

Differential Geometry · Mathematics 2008-11-19 Brendan Guilfoyle , Wilhelm Klingenberg

We investigate differential geometric properties of a parabolic point of a surface in the Euclidean three space. We introduce the contact cylindrical surface which is a cylindrical surface having a degenerate contact type with the original…

Differential Geometry · Mathematics 2023-02-01 Masaru Hasegawa , Yutaro Kabata , Kentaro Saji

Lagrangian curves in 4-space entertain intriguing relationships with second order deformation of plane curves under the special affine group and null curves in a 3-dimensional Lorentzian space form. We provide a natural affine symplectic…

Symplectic Geometry · Mathematics 2013-12-24 Emilio Musso , Evelyne Hubert

We study those Lagrangian surfaces in complex Euclidean space which are foliated by circles or by straight lines. The former, which we call cyclic, come in three types, each one being described by means of, respectively, a planar curve, a…

Differential Geometry · Mathematics 2009-09-18 Henri Anciaux , Pascal Romon

Let $\pi : E\to M$ be a smooth fiber bundle whose total space is a symplectic manifold and whose fibers are Lagrangian. Let $L$ be an embedded Lagrangian submanifold of $E$. In the paper we address the following question: how can one…

dg-ga · Mathematics 2008-02-03 Mikhail Entov

In this paper we construct and classify Lagrangian T^3-fibrations on non compact symplectic manifolds with singular fibres of prescribed topological type. This contributes to the understanding of the structure of the singular fibres that…

Symplectic Geometry · Mathematics 2009-08-13 Ricardo Castaño-Bernard

A wonderful compactification of an orbit under the action of a semi-simple and simply connected group is a smooth projective variety containing the orbit as a dense open subset, and where the added boundary divisor is simple normal…

Algebraic Geometry · Mathematics 2021-11-05 Elsa Corniani , Alex Massarenti

A membrane technique, in which the symplectic and Ricci forms are integrated over surfaces in a complexification of the phase space, as well a ``creation" connection with zero curvature over lagrangian submanifolds, is used to obtain a…

dg-ga · Mathematics 2008-02-03 Mikhail V. Karasev

Precise modeling of extended sources is a central challenge in modern optical engineering, laser physics, and computational lithography. Unlike ideal point sources or completely incoherent thermal radiation sources, real-world light sources…

Optics · Physics 2025-12-09 Rongqi Shang , Donglin Ma

We consider optimization problems on manifolds with equality and inequality constraints. A large body of work treats constrained optimization in Euclidean spaces. In this work, we consider extensions of existing algorithms from the…

Optimization and Control · Mathematics 2019-04-26 Changshuo Liu , Nicolas Boumal

We give a method to construct singular Lagrangian 3-torus fibrations over certain a priori given integral affine manifolds with singularities, which we call simple. The main result of this article is the proof that the topological…

Symplectic Geometry · Mathematics 2009-08-07 R. Castano-Bernard , D. Matessi

We investigate the caustic structure of a lens composed by a discrete number of point-masses, having mutual distances smaller than the Einstein radius of the total mass of the system. Along with the main critical curve, it is known that the…

Astrophysics · Physics 2007-05-23 Valerio Bozza

Optical (or Robinson) structures are one generalisation of four-dimensional shearfree congruences of null geodesics to higher dimensions. They are Lorentzian analogues of complex and CR structures. In this context, we extend the…

General Relativity and Quantum Cosmology · Physics 2015-03-17 Arman Taghavi-Chabert

We give a complete characterization of those disk bundles over surfaces which embed as rationally convex strictly pseudoconvex domains in $\mathbb{C}^2$. We recall some classical obstructions and prove some deeper ones related to symplectic…

Complex Variables · Mathematics 2016-02-05 Stefan Nemirovski , Kyler Siegel

The differential system for minimal Lagrangian surfaces in a $2_{\mathbb{C}}$-dimensional, non-flat, complex space form is an elliptic system defined on the bundle of oriented Lagrangian planes. This is a 6-symmetric space associated with…

Differential Geometry · Mathematics 2014-09-05 Joe S. Wang

The Eckardt hypersurface in $\mathbb{P}^{19}$ parameterizes smooth cubic surfaces with an Eckardt point, which is a point common to three of the $27$ lines on a smooth cubic surface. We describe the cubic surfaces lying on the singular…

Algebraic Geometry · Mathematics 2019-09-24 Hanieh Keneshlou