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48 results for Umbilical space

The study proves that pseudo-umbilical spacelike submanifolds are totally geodesic and totally umbilical.

problem Characterizing properties of pseudo-umbilical spacelike submanifolds in indefinite space forms.
method Derived an intrinsic inequality and used it to show total geodesic property. Proved total umbilicity using Aiyama's result.
result Pseudo-umbilical spacelike submanifolds are totally geodesic and totally umbilical.

Minimal totally real submanifolds in complex space forms have special umbilical properties.

problem Characterizing minimal totally real submanifolds in complex space forms.
method Analyzing the position of umbilical normal vectors in the normal bundle.
result Pseudo-umbilical totally real submanifolds with flat normal connection in non-flat complex space forms are minimal.

The paper finds conditions for certain hypersurfaces to be totally umbilical.

problem Conditions for constant mean curvature hypersurfaces to be totally umbilical.
method Analyzes the traceless part of the second fundamental form.
result Establishes conditions for complete constant mean curvature hypersurfaces to be totally umbilical.

For a regular surface in Euclidean space R3\mathbb{R}^3, umbilic points are precisely the points where the Gauss and mean curvatures KK and HH satisfy H2=KH^2=K; moreover, it is well-known that the only totally umbilic surfaces in R3\mathbb{R}^3 are planes and spheres. But for timelike surfaces in Minkowski space $\mat…

2010-06-22abs ↗pdf ↗

Paper characterizes umbilical hypersurfaces using a generalized overdetermined problem.

problem Characterizing umbilical hypersurfaces in space forms.
method Using a Serrin-type partially overdetermined problem with inhomogeneous Robin boundary condition.
result Any contact angle θ ∈ (0, π) can be achieved, generalizing previous results.

The study defines conditions for mean curvature of umbilical leaves in hyperbolic space.

problem Understanding mean curvature of umbilical leaves in hyperbolic space.
method Formulated necessary and sufficient conditions for a function along geodesics and hypercycles in hyperbolic space.
result Conditions for mean curvature of umbilical leaves are established for geodesics and hypercycles.

The paper studies quasi-umbilical timelike surfaces in a specific geometric setting.

problem Characterizing and understanding quasi-umbilical timelike surfaces in the (1+2)(1+2)-Einstein universe.
method Analyzes the conformal Lorentz geometry of these surfaces, proving their isothermic nature and constructing them from null curves.
result Quasi-umbilical surfaces are isothermic and their conformal deformations are determined by one arbitrary function.

Study on null hypersurfaces in complex contact manifolds.

problem Characterizing null hypersurfaces in indefinite complex contact manifolds.
method Proved classification results for various null hypersurfaces and characterized the ambient space.
result The ambient complex contact manifold must have constant GHGH-sectional curvature of 3-3 for certain null hypersurfaces.

Paper solves a mixed boundary value problem in space forms with umbilical boundaries.

problem Solving a partially overdetermined mixed boundary value problem in space forms.
method Generalizing previous results to domains with partial umbilical boundaries.
result A partially overdetermined problem in a domain with partial umbilical boundary admits a solution if and only if the rest part of the boundary is also part of an umbilical hypersurface.

Study finds unique totally umbilic null hypersurfaces in specific spacetimes.

problem Characterizing totally umbilic null hypersurfaces in generalized Robertson-Walker spaces.
method Established a correspondence between null hypersurfaces and fibre decompositions, proving uniqueness in certain models.
result Nullcones are the unique totally umbilic null hypersurfaces in the closed Friedmann Cosmological model.

The study characterizes submanifolds in product spaces.

problem Limited studies on pseudo-umbilical submanifolds.
method Using projections from product structure, conditions for submanifolds to be invariant, anti-invariant, or semi-invariant are derived.
result Necessary and sufficient conditions for pseudo-umbilical submanifolds in locally product Riemannian manifolds.

The study classifies totally umbilical surfaces in warped product manifolds.

problem Classifying totally umbilical surfaces in warped product manifolds.
method Analyzing surfaces in warped product M(κ)fimesI\mathbb{M}(κ)_f imes I and finding first integrals.
result Totally umbilical surfaces in M(κ)fimesI\mathbb{M}(κ)_f imes I are invariant by isometries.

The paper classifies submanifolds in pseudo-Riemannian space forms.

problem Characterizing and classifying totally umbilical submanifolds.
method Classification of congruent classes of totally umbilical submanifolds in non-flat pseudo-Riemannian space forms.
result Some moduli spaces of isometric immersions between space forms are non-Hausdorff.

New geometric proof shows index of umbilic points on analytic surfaces is at most one.

problem Proving the Carathéodory Conjecture for compact simply connected embedded surfaces.
method Geometric analysis of degenerate umbilic points on analytic surfaces.
result Index of an umbilic on an analytic surface cannot be an integer larger than one.

Study on real hypersurfaces in products of complex space forms, proving rigidity and nonexistence results.

problem Existence and properties of totally umbilical real hypersurfaces in complex space forms.
method Analyzing shape operators and local product structures in products of complex space forms.
result Nonexistence and rigidity results for totally umbilical real hypersurfaces in products of complex space forms.

The paper studies minimal submanifolds with specific curvature properties in Euclidean space.

problem Minimal submanifolds with (n2)(n-2)-umbilical properties in Euclidean space.
method Established a correspondence and developed a Weierstrass type method for local parametrization.
result Minimal, generic, (n2)(n-2)-umbilic submanifolds are (n2)(n-2)-rotational and have a parametric description.

New characterizations of umbilic hypersurfaces in warped product manifolds.

problem Characterizing umbilic hypersurfaces in specific warped product manifolds.
method Using a new integral formula or Brendle's Heintze-Karcher type inequality.
result Generalizations of classical theorems in Euclidean space to warped product manifolds.

A new definition of umbilic points at infinity for polynomial surfaces.

problem Defining umbilic points at infinity for homogeneous polynomial graphs.
method Proposed a stronger definition than Toponogov's, proving all are isolated and pairs, with geometric interpretation.
result All umbilic points at infinity are isolated and occur in pairs, being zeroes of the projective extension of the third fundamental form.

A spacelike surface S immersed in a 4-dimensional Lorentzian manifold will be said to be umbilical along a direction N normal to S if the second fundamental form along N is proportional to the first fundamental form of S. In particular, S is pseudo-umbilical if it is umbilical along the mean curvature vector field H, a…

2011-11-29abs ↗pdf ↗

Study on umbilical submanifolds in specific geometric spaces.

problem Characterizing curvature properties of umbilical submanifolds.
method Analyzing totally and screen totally umbilical half lightlike submanifolds in almost contact B-metric manifolds.
result Curvature properties of these submanifolds were studied and characterized.

We give a complete classification of umbilical surfaces of arbitrary codimension of a product Qk1n1×Qk2n2Q^{n_1}_{k_1}\times Q^{n_2}_{k_2} of space forms whose curvatures satisfy k1+k20k_1 + k_2 \not= 0.

2013-10-09abs ↗pdf ↗

The paper describes the CR umbilical locus of a real ellipsoid in complex space.

problem Characterizing the CR umbilical locus of a real ellipsoid in complex space.
method Analyzing the set of points where the ellipsoid can be osculated by a biholomorphic image of the sphere up to 6th order.
result The CR umbilical locus is the union of stable curves and a non-trivial real variety defined by sextic equations.

In this article, we prove new stability results for almost-Einstein hypersurfaces of the Euclidean space, based on previous eigenvalue pinching results. Then, we deduce some comparable results for almost umbilical hypersurfaces.

2007-10-26abs ↗pdf ↗