In this work, we study plane and spherical curves in Euclidean and Lorentz-Minkowski 3-spaces by employing rotation minimizing (RM) frames. By conveniently writing the curvature and torsion for a curve on a sphere, we show how to find the angle between the principal normal and an RM vector field for spherical curves. L…
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48 results for “spherical plane”
The paper explores geometric properties of interception curves on planes and spheres.
problem Geometric properties of interception curves defined by differential equations.
method Parametric representation and spherical curve defined by Gudermannian function.
result Symmetry/asymmetry between spherical and planar cases, connections to lemniscate constants.
Derives a formula for fermion dimensions in spherically symmetric monopole backgrounds.
problem Calculating the dimension of the plane-wave normalizable kernel for massless fermions in spherically symmetric monopole backgrounds.
method Derives a formula for the dimension of the plane-wave normalizable kernel of the Dirac operator for fermions of any representation of SU(N) in the presence of any spherically symmetric monopole background.
result Derives a formula for the dimension of the plane-wave normalizable kernel of the Dirac operator.
We present a method to construct a large family of Lagrangian surfaces in complex Euclidean plane by using Legendre curves in the 3-sphere and in the anti de Sitter 3-space or, equivalently, by using spherical and hyperbolic curves, respectively. Among this family, we characterize minimal, constant mean curvature, Hami…
It is known that the space of convex polygons in the Euclidean plane with fixed normals, up to homotheties and translations, endowed with the area form, is isometric to a hyperbolic polyhedron. In this note we show a class of convex polygons in the Lorentzian plane such that their moduli space, if the normals are fixed…
Study calculates eigenvalues and eigenfunctions for spherical triangles and finds fundamental gap behavior.
problem Understanding eigenvalues and gaps in spherical triangles.
method Explicit computation of Dirichlet eigenvalues and eigenfunctions for spherical lunes and triangles.
result Fundamental gap of spherical triangles increases as the angle of the lune decreases.
Proof of Graustein's theorem in different geometries.
problem Average curvature of plane ovals and convex curves in various geometries.
method Wave propagation approach for different geometries.
result The average curvature is attained at least at four points in different geometries.
We describe the evolution under the mean curvature flow of embedded Lagrangian spherical surfaces in the complex Euclidean plane . In particular, we answer the Question 4.7 addressed in [Ne10b] by A. Neves about finding out a condition on a starting Lagrangian torus in such that the corresp…
It is shown that the initial singularities in spatially compact spacetimes with spherical, plane or hyperbolic symmetry admitting a compact constant mean curvature hypersurface are crushing singularities when the matter content of spacetime is described by the Vlasov equation (collisionless matter) or the wave equation…
Spherical arc-length as a global conformal parameter for analytic curves in the Riemann spheremath.CV
We prove that for every analytic curve in the complex plane, Euclidean and spherical arc-lengths are global conformal parameters. We also prove that for any analytic curve in the hyperbolic plane, hyperbolic arc-length is also a global parameter. We generalize some of these results to the case of analytic curves in Euc…
Dunkl connections on complex plane don't preserve metrics.
problem Preserving metrics with Dunkl connections on \(\mathbb{C}^2\).
method Analysis of the topology of spherical tori with conical points.
result General Dunkl connections on \(\mathbb{C}^2\) do not preserve non-zero Hermitian forms.
We show that every spherical 2-Dupin submanifold that is not a hypersurface is conformally congruent to the standard embedding of the real, complex, quaternionic or octonionic projective plane. We also classify 2-CPC, 2-umbilical and weakly 2-umbilical submanifolds in space forms.
On the spherical clothoidmath.DG
Researchers found new functions for spherical clothoids using special functions.
problem Developing new mathematical functions for spherical clothoids.
method Used confluent hypergeometric functions and Meixner-Pollaczek polynomials.
result Presented Cartesian coordinate functions and stereographic projections.
Paper extends Schur's theorem to spherical curves via monotonicity.
problem Comparing chord lengths of convex and spherical curves.
method Monotonicity and expansion module approach.
result Schur's Theorem extended to spherical curves.
Radial expansion preserves hyperbolic convexity and radial contraction preserves spherical convexitymath.DG
Convexity properties are preserved under radial transformations in hyperbolic and spherical geometries.
problem Preserving convexity in hyperbolic and spherical geometries under radial transformations.
method Used Poincaré disk model for hyperbolic geometry and stereographic projection for spherical geometry to prove preservation of convexity under radial expansion and contraction.
result Radial expansion and contraction preserve hyperbolic and spherical convexity, respectively.
Analyzes packing of circles in bounded and unbounded planes using mathematical formulas.
problem Finding optimal radii for packing circles in various plane regions.
method Deterministic analytic formulae and recurrence relations.
result Formulated analytic formulae for 2D circle packing on various plane shapes.
We determine the contributions of isolated singularities of spin V 4-manifolds to the index of the Dirac operator over them. From these data we derive certain constraints on the intersection forms of spin 4-manifolds bounded by spherical 3-manifolds, and also on the embeddings of the real projective planes into 4-manif…
The paper extends Euler's problem to hyperbolic and spherical planes.
problem Extending Euler's problem to hyperbolic and spherical planes.
method Characterizing critical points of moment of inertia energy in hyperbolic and spherical planes.
result Closed stationary curves in hyperbolic plane are circles centered at N.
We apply a spherical CR Dehn surgery theorem in order to obtain infinitely many Dehn surgeries of the Whitehead link complement that carry spherical CR structures. We consider as starting point the spherical CR uniformization of the Whitehead link complement constructed by Parker and Will, using a Ford domain in the co…
The study extends inscription problems to non-Euclidean geometries.
problem Generalizing inscription problems to non-Euclidean geometries.
method Symplectic and Riemannian geometry techniques.
result Proved generalized inscription theorems for hyperbolic and spherical surfaces.
New patterns on spheres and hyperbolic planes described by integrable systems.
problem Integrable systems and variational principles for spherical and hyperbolic ring patterns.
method Discrete integrable system, variational principles, elliptic dilogarithm function.
result Existence and uniqueness of ring patterns for Dirichlet and Neumann problems.
The stick index of a knot is the least number of line segments required to build the knot in space. We define two analogous 2-dimensional invariants, the planar stick index, which is the least number of line segments in the plane to build a projection, and the spherical stick index, which is the least number of great c…
Optimal inequality on sphere for convex bodies.
problem Bounding the spherical measure of a convex body's intersection with a plane orthogonal to its centroid.
method Proving an inequality on the sphere using convex geometry.
result The inequality is optimal with a constant of \((1-1/n)^{n-1}\).
In this paper, we exploit a subtle indeterminacy in the definition of the spherical Kervaire-Milnor invariant which was discovered by R. Stong to construct non-spin 4-manifolds with even intersection form and prescribed signature.
Recent advances in twistor theory are applied to geometric optics in . The general formulae for reflection of a wavefront in a surface are derived and in three special cases explicit descriptions are provided: when the reflecting surface is a plane, when the incoming wave is a plane and when the incoming w…
We study singularities of constant positive Gaussian curvature surfaces and determine the way they bifurcate in generic 1-parameter families of such surfaces. We construct the bifurcations explicitly using loop group methods. Constant Gaussian curvature surfaces correspond to harmonic maps, and we examine the relations…
On a class of systems of hyperbolic equations describing pseudo-spherical or spherical surfacesmath.DG
Abstract: Studies systems of equations for pseudo-spherical or spherical surfaces, finding integrability conditions and new families of equations.
problem Characterize and classify systems of equations describing pseudo-spherical or spherical surfaces.
method Integrability conditions of -valued linear problems, with or .
result Obtained characterization and classification results, providing new examples and families of differential equations.
The consideration of the so-called rotation minimizing frames allows for a simple and elegant characterization of plane and spherical curves in Euclidean space via a linear equation relating the coefficients that dictate the frame motion. In this work, we extend these investigations to characterize curves that lie on a…
Spherical representations and functions are the building blocks for harmonic analysis on riemannian symmetric spaces. In this paper we consider spherical functions and spherical representations related to certain infinite dimensional symmetric spaces . We use the representation t…
Let M be a complete Riemannian manifold whose sectional curvature is bounded above by 1. We say that M has positive spherical rank if along every geodesic one hits a conjugate point at t=π. The following theorem is then proved: If M is a complete, simply connected Riemannian manifold with upper curvature bound 1 and po…
We study the motion of a particle in the hyperbolic plane (embedded in Minkowski space), under the action of a potential that depends only on one variable. This problem is the analogous to the spherical pendulum in a unidirectional force field. However, for the discussion of the hyperbolic plane one has to distinguish …
Minimal surfaces in 4D space are stable if their Gauss map spherical area is less than 2π.
problem Stability of minimal surfaces in 4D space.
method Geometric criteria based on the Gauss map of minimal surfaces in terms of the spherical area.
result Minimal surfaces in 4D space are stable if their Gauss map spherical area is less than 2π.
A non-Newtonian approach in differential geometry of curves: multiplicative rectifying curvesmath.DG
Study rectifying curves in 3D multiplicative Euclidean space.
problem Investigate rectifying curves in a non-Newtonian geometry setting.
method Apply multiplicative differential-geometric concepts to rectifying curves.
result Classify multiplicative rectifying curves using spherical curves.
Tripod configurations of plane curves, formed by certain triples of normal lines coinciding at a point, were introduced by Tabachnikov, who showed that closed convex curves possess at least two tripod configurations. Later, Kao and Wang established the existence of tripod configurations for closed locally c…
The paper defines functions from spherical curves and chord diagrams, proving invariance under specific Reidemeister moves.
problem Defining and proving invariance of functions derived from spherical curves and chord diagrams.
method Introducing and functions, and defining relators of Type (I) ((SII), (WII), (SIII), or (WIII), resp.).
result If vanishes for the relators of Type (I) ((SII), (WII), (SIII), or (WIII), resp.), then is invariant under specific Reidemeister moves.
We consider congruences of straight lines in a plane with the combinatorics of the square grid, with all elementary quadrilaterals possessing an incircle. It is shown that all the vertices of such nets (we call them incircular or IC-nets) lie on confocal conics. Our main new results are on checkerboard IC-nets in the p…
New moving plane method for varifolds promotes smoothness from boundary to interior.
problem Promoting smoothness from boundary to interior for singular hypersurfaces.
method Introduced a moving plane method for varifolds, showing smoothness as a conclusion.
result Smoothness and symmetry in the interior can be promoted from smoothness and symmetry at infinity.
Napoleonic triangles don't exist in hyperbolic geometry.
problem The existence of Napoleonic triangles in hyperbolic geometry.
method Analyzing the construction of equilateral triangles on hyperbolic triangles.
result Hyperbolic triangles do not form Napoleonic triangles, except equilateral ones.
The paper explores centroids and static equilibrium points in non-Euclidean geometries.
problem Investigating centroids and static equilibrium points in spherical, hyperbolic, and normed spaces.
method Extending Gal'perin's work, the paper examines convex bodies in these spaces and analyzes the minimum number of equilibrium points.
result Every plane convex body in any of these spaces has at least four equilibrium points, and there are mono-monostatic convex bodies in 3D spherical, hyperbolic, and certain normed spaces.
Model predicts growth competition on curved surfaces.
problem Growth dynamics of two subsets on Riemannian manifolds.
method Modeling growth rates on spherically symmetric Riemannian manifolds.
result Conditions for bounded or unbounded growth on different manifolds.
New minimal annuli found in unit ball, solving old problems.
problem Constructing free boundary minimal annuli in unit ball.
method Symmetric and foliated by spherical curvature lines.
result First non-embedded free boundary minimal annuli in unit ball.
A new method tracks retinal vessels more accurately than existing methods.
problem Tracking retinal vessels accurately in spherical images.
method Computing cusp-free, crossing-preserving geodesics on spherical positions and orientations.
result Crossing-preserving tracking shows clear advantages over non-crossing-preserving tracking.
The paper examines curvature and stability in quasi-geostrophic motions using spherical harmonics.
problem Analyzing the curvature and stability of quasi-geostrophic motions.
method Utilizing spherical harmonics and structure constants, the curvature of the metric on the central extension is computed.
result A lower bound for weather prediction error in a simplified model is suggested.
Two classification results for stationary surfaces of least moment of inertia.
problem Classifying stationary surfaces in Euclidean space based on their energy.
method Analyzing ruled and foliated surfaces, using critical point theory.
result Classification of stationary surfaces including vector planes, elongated helicoids, and specific types of surfaces.
Minimal networks on S^2math.DG
The paper extends minimal network theory to the sphere, proving local minimality.
problem Finding networks of minimal length on the sphere.
method Adapted spherical geometry, calibration method, and local metric perturbation estimates.
result Spherical minimal networks composed of great-circle arcs are locally length-minimizing within small geodesic balls.
Louis Poinsot has shown in 1854 that the motion of a rigid body, with one of its points fixed, can be described as the rolling without slipping of one cone, the 'body cone', along another, the 'space cone', with their common vertex at the fixed point. This description has been further refined by the second author in 19…
The paper proves rigidity theorems for area widths of Riemannian manifolds.
problem Characterizing metrics on Riemannian manifolds using their area widths.
method Analyzing the volume spectrum and spherical area widths.
result Rigidity theorems for specific metrics on projective spaces.
The study classifies horo-shrinkers in hyperbolic space under different isometries.
problem Characterizing horo-shrinkers in hyperbolic space under various isometries.
method Analyzing horo-shrinkers invariant by one-parameter groups of hyperbolic, parabolic, and spherical isometries.
result Grim reapers are defined as horo-shrinkers invariant by parabolic translations and are periodic surfaces.