The paper studies half-lightlike submanifolds in Lorentzian manifolds with specific distributions.
problem Characterizing half-lightlike submanifolds in Lorentzian manifolds with conformal co-screen distributions.
method Using Cartan's formula, the authors classify half-lightlike submanifolds of Lorentzian space forms with constant screen principal curvatures.
result Screen homothetic half-lightlike submanifolds of a Lorentzian space form with a conformal co-screen distribution are locally lightlike triple product manifolds.
In this paper we develop the notion of screen isoparametric hypersurface for null hypersurfaces of Robertson-Walker spacetimes. Using this formalism we derive Cartan identities for the screen principal curvatures of null screen hypersurfaces in Lorentzian space forms and provide a local characterization of such hypersu…
Study Einstein warped-product manifolds with specific curvature conditions.
problem Understanding Einstein warped-product manifolds with screened Poisson equation constraints.
method Analyzing manifolds with specific curvature conditions and solving the screened Poisson equation.
result Dimension, Ricci curvature, and screened parameter are related through a quadratic equation.
A pp-wave is a Lorentzian manifold with a parallel light-like vector field satisfying a certain curvature condition. We introduce generalisations of pp-waves, on one hand by allowing the vector field to be recurrent and on the other hand by weakening the curvature condition. These generalisations are related to the scr…
New types of null hypersurfaces found in Sasakian space-forms.
problem Identifying new structures in Sasakian space-forms.
method Defined and analyzed contact screen conformal and umbilic null hypersurfaces.
result Proved these hypersurfaces exist in Sasakian space forms with specific curvature.
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 GH-sectional curvature of −3 for certain null hypersurfaces. Study on special null submanifolds in indefinite Sasakian manifolds.
problem Characterizing null submanifolds in indefinite Sasakian manifolds.
method Proving properties of screen conformal null submanifolds and defining a new class.
result Existence of contact screen conformal r-null submanifolds in indefinite Sasakian space forms. Study of null hypersurfaces in semi-Riemannian manifolds with applications.
problem Characterize null hypersurfaces in semi-Riemannian manifolds with varying sectional curvature.
method Introduce screen quasi-conformal hypersurfaces and extend results to non-zero sectional curvature.
result Classification results for umbilical, isoparametric, and Einstein null hypersurfaces in Lorentzian space forms.
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.
Novel approximation hierarchy for sparse quadratic programs.
problem Sparse Quadratic Programs with Cardinality Constraints.
method Exploits rank-dominating eigenvectors for min-max optimization over binary variables.
result Efficient screening of nonzero elements with scalable optimization algorithms.
We derive total mean curvature integration formulae of a three co-dimensional foliation Fn on a screen integrable half-lightlike submanifold, Mn+1 in a semi-Riemannian manifold Mn+3. We give generalized differential equations relating to mean curvatures of a totally umbilical half-li…
The paper classifies and determines properties of specific hypersurfaces in complex hyperbolic quadrics.
problem Analyzing Hopf hypersurfaces with constant principal curvatures in complex hyperbolic quadrics.
method Classification and determination of principal curvatures for hypersurfaces with different numbers of distinct curvatures.
result Classification and determination of principal curvatures for Hopf hypersurfaces with up to four distinct values.
Study on isoparametric and constant-curvature hypersurfaces in Finsler spaces.
problem Characterizing and constructing hypersurfaces with specific curvature properties in Finsler geometry.
method Analyzing isoparametric and constant-curvature hypersurfaces on Randers manifolds.
result Construction of a conformally flat Randers manifold with nonisoparametric hyperplanes of constant curvatures.
Study on discrete surfaces with constant principal curvature for nanocarbon applications.
problem Understanding discrete geometry properties of nanocarbon materials.
method Developed discrete surface theory on 3-ary oriented trees, defined discrete principal directions, constructed examples of discrete CPC surfaces.
result Construction of discrete constant principal curvature surfaces, including discrete CPC tori.
Study behavior of curvatures near singular points of frontals.
problem Understanding frontals near singular points.
method Investigate principal curvatures and vectors near singular points of frontals.
result Extend Ribaucour transformations to frontals with singular points.
Study on hypersurfaces with specific curvature conditions.
problem Characterizing hypersurfaces with certain curvature properties.
method Defined and analyzed the Opozda-Verstraelen affine curvature tensor for hypersurfaces.
result Conditions for pseudosymmetry types of hypersurfaces with specific curvature properties.
Classifies surfaces with special curvature properties.
problem Rotational surfaces with specific curvature conditions.
method Classifies surfaces with rotationally symmetric norms and linear curvature relations.
result Rotational surfaces with linearly related curvatures are classified.
The paper studies Einstein hypersurfaces in a specific warped product space.
problem Investigating Einstein hypersurfaces in a warped product space.
method Analyzing the principal curvatures and using multiply warped product structure.
result Hypersurfaces have at most three distinct principal curvatures and are locally multiply warped products.
Study the geometry of a surface formed by extending a Whitney umbrella.
problem Investigate the geometric properties of a specific surface formed by extending a Whitney umbrella.
method Analyze the intersection with the normal plane, geodesic and normal curvatures, Gaussian and mean curvatures.
result Determine the zeros of curvature functions and deduce geometric relationships.
In this paper are determined the principal curvatures and principal curvature lines on canal surfaces which are the envelopes of families of spheres with variable radius and centers moving along a closed regular curve in R^3. By means of a connection of the differential equations for these curvature lines and real Ricc…
The paper classifies Hopf hypersurfaces with constant curvatures on complex quadrics.
problem Classifying Hopf hypersurfaces with specific curvature properties.
method Analyzing hypersurfaces on complex quadrics with at most five distinct constant principal curvatures.
result All classified hypersurfaces are open parts of homogeneous examples.
The study examines principal directions and curvatures of Lagrangian submanifolds.
problem Understanding the geometry of Lagrangian submanifolds.
method Recalling and analyzing the extrinsic principal tangential and normal directions, and their corresponding curvatures for Lagrangian submanifolds in complex Euclidean spaces.
result Established natural relationships between distinguished tangential and normal directions and their curvatures for Lagrangian submanifolds.
We consider convex hypersurfaces for which the ratio of principal curvatures at each point is bounded by a function of the maximum principal curvature with limit 1 at infinity. We prove that the ratio of circumradius to inradius is bounded by a function of the circumradius with limit 1 at zero. We apply this result to …
If M is an isoparametric hypersurface in a sphere Sn with four distrinct principal curvatures, then the principal curvatures κ1,...,κ4 can be ordered so that their multiplicities satisfy m1=m2 and m3=m4, and the cross-ratio r of the principal curvatures (the Lie curvature) equals -1. In this paper, w…
Study disproves a conjecture about constant curvature hypersurfaces.
problem Whether every hypersurface with constant principal curvatures is isoparametric.
method Constructed an explicit example of a conformally flat Riemannian manifold.
result Disproved the conjecture by providing a counterexample.
Researchers compute differential invariants for Carrollian spacetimes.
problem Understanding the geometry and symmetries of Carrollian spacetimes.
method Derived from the geometry of the screen bundle, computed differential invariants using jet-spaces and Spencer cohomology.
result Specified how to generate the entire algebra of differential invariants for generic Carrollian structures, focusing on dimension 3.
The purpose of the present work is to study (marginally) trapped submanifolds lying in a null hypersurface. Let $(M,g,N)\to\Bm(c)$ be a null hypersurface of a space-time with constant sectional curvature c, endowed with a Screen Integrable and Conformal rigging N. The (Marginally) Trapped Submanifolds we are intere…
The paper constructs all cmc hypersurfaces with two principal curvatures.
problem Finding all hypersurfaces with constant mean curvature and two principal curvatures.
method Explicit immersions and parameter analysis for hypersurfaces in space forms.
result The family of cmc hypersurfaces with two principal curvatures depends on two parameters, H and C.
The paper shows nearly-Fuchsian properties for certain hyperbolic 3-manifolds.
problem Characterizing hyperbolic 3-manifolds with specific surface properties.
method Analyzing minimal and non-minimal surfaces with principal curvatures in [-1,1](-1,1).
result Weakly almost-Fuchsian manifolds are nearly-Fuchsian.
In this paper, we have studied biharmonic hypersurfaces in space form Mˉn+1(c) with constant sectional curvature c. We have obtained that biharmonic hypersurfaces Mn with at most three distinct principal curvatures in Mˉn+1(c) has constant mean curvature. We also obtain the full classificatio…
Study surfaces with constant ratio of principal curvatures in Euclidean and isotropic geometries.
problem Characterize surfaces with constant ratio of principal curvatures in different geometries.
method Differential geometry, line geometry, Lie sphere geometry, ordinary differential equations, algebraic geometry.
result Characterized various types of surfaces like rotational, channel, ruled, helical, and translational.
Lie minimal surfaces are characterized by differential equations of principal curvatures.
problem Characterizing Lie minimal surfaces in Riemannian space forms.
method Using Euler-Lagrange equations and differential equations of principal curvatures.
result Rotational surfaces are found for certain relationships between principal curvatures.
Principal binets generalize curvature line surfaces to square lattices and are a discrete integrable system.
problem Discretizing curvature line surfaces on square lattices.
method Showed principal binets as a multi-dimensional consistent system.
result Principal binets generalize to higher-dimensional square lattices and are integrable.
We find the first examples of real hypersurfaces with two nonconstant principal curvatures in complex projective and hyperbolic planes, and we classify them. It turns out that each such hypersurface is foliated by equidistant Lagrangian flat surfaces with parallel mean curvature or, equivalently, by principal orbits of…
We classify all real hypersurfaces with constant principal curvatures in the complex hyperbolic plane.
The paper proves a stronger Petersen--Wilhelm conjecture for principal bundles.
problem Conditions for positive sectional curvature submersion metrics on principal bundles.
method Cheeger deformations, good triples, Chaves-Derdzinski-Rigas type condition.
result Any principal bundle over a positively curved base admits a metric of positive sectional curvature if the submersion is fat.
The study examines connections and their curvatures on different types of bundles.
problem Understanding connections and curvatures on various bundle types.
method Analysis of connections and curvatures on fiber, principal, and vector smooth bundles.
result Investigations into the relationships between connections and curvatures on different bundle types.
We study principal curvatures of fibers and Heegaard surfaces smoothly embedded in hyperbolic 3-manifolds. It is well known that a fiber or a Heegaard surface in a hyperbolic 3-manifold cannot have principal curvatures everywhere less than one in absolute value. We show that given an upper bound on the genus of a minim…
We consider surfaces in Euclidean space parametrized on an annular domain such that the first fundamental form and the principal curvatures are rotationally invariant, and the principal curvature directions only depend on the angle of rotation (but not the radius). Such surfaces generalize the Enneper surface. We show …
We study surfaces with one constant principal curvature in Riemannian and Lorentzian three-dimensional space forms. Away from umbilic points they are characterized as one-parameter foliations by curves of constant curvature, each of these curves being centered at a point of a regular curve and contained in its normal p…
We classify all real hypersurfaces with three distinct constant principal curvatures in complex hyperbolic spaces of dimension greater than two.
The study examines spacelike hypersurfaces in Minkowski space with constant σn−1 curvature.
problem Characterizing spacelike hypersurfaces with constant σn−1 curvature in Minkowski space. method Analyzing hypersurfaces with bounded principal curvatures and proving properties of their convexity.
result Hypersurfaces with constant σn−1 curvature in Minkowski space are either convex or can be split into a product form. The study classifies hypersurfaces with constant principal curvatures in S3imesR and H3imesR.
problem Classifying hypersurfaces with constant principal curvatures in specific product spaces.
method Analyzing isoparametric surfaces and using isoparametric properties to classify hypersurfaces.
result Hypersurfaces with constant principal curvatures are cylinders over isoparametric surfaces in Q3. The paper characterizes surfaces using invariants.
problem Determining surfaces in 3D space without umbilical points.
method Introducing canonical principal parameters and using invariants (principal curvatures or Gauss and mean curvature) to uniquely identify surfaces.
result Surfaces are uniquely determined by a pair of invariants satisfying a partial differential equation.
The paper proves properties of triharmonic CMC hypersurfaces with specific curvature conditions.
problem Characterizing triharmonic CMC hypersurfaces with distinct principal curvatures.
method Analyzing critical points of the tri-energy and applying geometric properties.
result Proves conditions for constant scalar curvature and minimality of hypersurfaces.
RaSE screens variables via random subspaces, identifying joint effects.
problem Missing joint effects of predictors in ultra-high dimensional data.
method Random Subspace Ensemble (RaSE) framework combining subspace evaluation criteria.
result RaSE identifies signals with no marginal effect or high-order interactions.
Classifies hypersurfaces with specific curvature properties in 4D space.
problem Classifying hypersurfaces with three distinct principal curvatures in 4D space.
method Used classification results for hypersurfaces in R4, S3imesR, and H3imesR to derive new classifications. result Alternative classification of cyclic conformally flat hypersurfaces in R4. We classify the homogeneous and isoparametric hypersurfaces of S2×S2. In the classification, besides the hypersurfaces S1(r)×S2,r∈(0,1], it appears a family of hypersurfaces with three different constant principal curvatures and zero Gauss-Kronecker curvature. …