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48 results for Willmore surfaces

Spacelike Willmore surfaces in 4-dimensional Lorentzian space forms, a topic in Lorentzian conformal geometry which parallels the theory of Willmore surfaces in S4S^4, are studied in this paper. We define two kinds of transforms for such a surface, which produce the so-called left/right polar surfaces and the adjoint s…

2007-09-12abs ↗pdf ↗

Let $ X: M \hook S^5$ be a compact Legendrian surface in pseudoconformal(CR) 5-sphere. We introduce a pseudoconformally invariant Willmore type second order functional $ \W(X)$, and study its critical points called Willmore Legendrian surfaces. The fifth order structure equations show that Willmore dual can be defined …

2007-07-03abs ↗pdf ↗

The paper discusses Gauss maps for Möbius surfaces in spheres and their applications to Willmore surfaces.

problem Understanding Gauss maps and their relation to Willmore surfaces in spheres.
method Definition and study of Lorentzian 2-plane lifts for Möbius surfaces, and equivalence to Willmore condition.
result The conformal harmonicity of a Lorentzian 2-plane lift is equivalent to the Willmore condition for a surface.

We study a class of fourth-order geometric problems modelling Willmore surfaces, conformally constrained Willmore surfaces, isoperimetrically constrained Willmore surfaces, bi-harmonic surfaces in the sense of Chen, among others. We prove several local energy estimates and derive a global gap lemma.

2018-11-21abs ↗pdf ↗

In this paper we develop the theory of Willmore sequences for Willmore surfaces in the 4-sphere. We show that under appropriate conditions this sequence has to terminate. In this case the Willmore surface either is the twistor projection of a holomorphic curve into complex projective space or the inversion of a minimal…

2006-10-21abs ↗pdf ↗

The classification of Willmore 2-spheres in the nn-dimensional sphere SnS^n is a long-standing problem, solved only when n=3,4n=3,4 by Bryant, Ejiri, Musso and Montiel independently. In this paper we give a classification when n=5n=5. There are three types of such surfaces up to Möbius transformations: (1) super-conformal…

2014-09-08abs ↗pdf ↗

We view conformal surfaces in the 4--sphere as quaternionic holomorphic curves in quaternionic projective space. By constructing enveloping and osculating curves, we obtain new holomorphic curves in quaternionic projective space and thus new conformal surfaces. Applying these constructions to Willmore surfaces, we show…

2003-06-09abs ↗pdf ↗

A neural flow method minimizes Willmore energy for 2-surfaces in 3D space.

problem Minimizing Willmore energy for closed oriented 2-surfaces in 3D space.
method Introducing neural Willmore flow to model and minimize the Willmore energy using neural architectures.
result The neural flow reproduces expected round sphere and Clifford torus for genus 0 and 1 surfaces, respectively, and finds minimal Willmore surfaces for genus 2.

The Willmore flow preserves surface volume, leading to convergence to a sphere.

problem Long-term behavior of volume-preserving Willmore flow on surfaces.
method Volume-preserving Willmore flow, blow-up analysis, constrained Lojasiewicz-Simon inequality.
result Smooth solutions exist for spherical surfaces with Willmore energy below 8π and converge to a sphere.

In this note we demonstrate how the analogy between the harmonic Gauss map of a constant mean curvature surface and the harmonic conformal Gauss map of a Willmore surface can be used to obtain results on Willmore surfaces.

2010-03-17abs ↗pdf ↗

The study constructs equivariant harmonic maps into symmetric spaces with applications to Willmore surfaces.

problem Constructing harmonic maps into symmetric spaces.
method Equivariant primitive harmonic maps construction.
result Examples of S1S^1-equivariant Willmore Moebius strips in S3S^3.

The paper shows deformations between minimal surfaces in Sn+2S^{n+2} and Hn+2H^{n+2}.

problem Deformation of minimal surfaces between Sn+2S^{n+2} and Hn+2H^{n+2}.
method Willmore deformation approach.
result Existence of smooth families of Willmore surfaces connecting minimal surfaces in Sn+2S^{n+2} and Hn+2H^{n+2}.

In this paper we build an explicit example of a minimal bubble on a Willmore surface, showing there cannot be compactness for Willmore immersions of Willmore energy above 16π16 π. Additionnally we prove an inequality on the second residue for limits sequences of Willmore immersions with simple minimal bubbles. Doing so,…

2019-06-01abs ↗pdf ↗

We develop a general Minmax procedure in Euclidian spaces for constructing Willmore surfaces of non zero indices. We implement this procedure to the Willmore Minmax Sphere Eversion in the 3 dimensional euclidian space. We compute the cost of the Sphere eversion in terms of Willmore energies of Willmore Spheres in ${\R}…

2015-12-30abs ↗pdf ↗

We discuss several kinds of Willmore surfaces of flat normal bundle in this paper. First we show that every S-Willmore surface with flat normal bundle in SnS^n must locate in some S3SnS^3\subset S^n, from which we characterize Clifford torus as the only non-equatorial homogeneous minimal surface in SnS^n with flat normal…

2013-01-13abs ↗pdf ↗

The study classifies surfaces in Berger spheres as Willmore and Hopf tori.

problem Classifying surfaces in Berger spheres as Willmore and Hopf tori.
method Defined a Willmore functional for surfaces in homogeneous spaces and computed its variational formula. Characterized Clifford and Hopf tori as Willmore surfaces satisfying a sharp inequality.
result Clifford and Hopf tori are the only Willmore surfaces in Berger spheres satisfying a specific inequality.

We found a new formulation to the Euler-Lagrange equation of the Willmore functional for immersed surfaces in Rm{\R}^m. This new formulation of Willmore equation appears to be of divergence form, moreover, the non-linearities are made of jacobians. Additionally to that, if $\bH$ denotes the mean curvature vector of the…

2006-12-18abs ↗pdf ↗

Study compact Willmore surfaces without complex structure convergence, computing energy loss and geodesic lengths.

problem Compactness of Willmore surfaces without complex structure convergence.
method Compute energy loss in neck and geodesic lengths in Grassmannian G(2,n)G(2,n).
result Limit of Gauss map image is a geodesic in G(2,n)G(2,n) with computable length.

Constrained Willmore surfaces are conformal immersions of Riemann surfaces that are critical points of the Willmore energy W=H2W=\int H^2 under compactly supported infinitesimal conformal variations. Examples include all constant mean curvature surfaces in space forms. In this paper we investigate more generally the crit…

2004-11-22abs ↗pdf ↗

After the surface theory of Möbius geometry, this study concerns a pair of conformally immersed surfaces in nn-sphere. Two new invariants θθ and ρρ associated with them are introduced as well as the notion of touch and co-touch. This approach is helpful in research about transforms of certain surface classes. As an …

2005-08-08abs ↗pdf ↗

This is the first comprehensive introduction to the authors' recent attempts toward a better understanding of the global concepts behind spinor representations of surfaces in 3-space. The important new aspect is a quaternionic-valued function theory, whose "meromorphic functions" are conformal maps into quaternions, wh…

2000-02-10abs ↗pdf ↗

Study of large area-constrained Willmore surfaces in Schwarzschild-like manifolds.

problem Understanding Willmore surfaces in asymptotically Schwarzschild 3-manifolds.
method Application of Lyapunov-Schmidt reduction method.
result End of the manifold is foliated by area-constrained Willmore spheres.

We use the dressing method to construct transformations of constrained Willmore surfaces in arbitrary codimension. An adaptation of the Terng--Uhlenbeck theory of dressing by simple factors to this context leads us to define Bäcklund transforms of these surfaces for which we prove Bianchi permutability. Specialising to…

2013-07-08abs ↗pdf ↗

Willmore flow converges globally for surfaces with rotational symmetry below a specific energy threshold.

problem Global existence and convergence of Willmore flow with Dirichlet boundary conditions.
method Considered surfaces with rotational symmetry, proved global existence and convergence for initial data below a sharp energy threshold.
result Sharp threshold for global existence and convergence of Willmore flow depends on boundary conditions.

Ejiri's torus in S5S^5 is the first example of Willmore surface which is not conformally equivalent to any minimal surface in any space forms. Li and Vrancken classified all Willmore surfaces of tensor product in SnS^{n} by reducing them into elastic curves in S3S^3, and the Ejiri torus appeared as a special example. I…

2015-01-27abs ↗pdf ↗

The paper studies Willmore surfaces in 4D conformal manifolds and finds the Clifford torus is strictly Willmore-stable.

problem Exploring the Willmore functional for surfaces in 4D conformal manifolds.
method Detailed calculation of first and second variations, derivation of Euler-Lagrange equation in a conformally invariant form.
result The Clifford torus in CP2\mathbb{C}P^2 is strictly Willmore-stable, supporting a conjecture.

Willmore surfaces are the extremals of the Willmore functional (possibly under a constraint on the conformal structure). With the characterization of Willmore surfaces by the (possibly perturbed) harmonicity of the mean curvature sphere congruence [Blaschke, Ejiri, Rigoli, Burstall-Calderbank], a zero-curvature formula…

2011-12-30abs ↗pdf ↗

We prove a bubble-neck decomposition together with an energy quantization result for sequences of Willmore surfaces into an arbitrary euclidian space with uniformly bounded energy and non-degenerating conformal type. We deduce the strong compactness of Willmore closed surfaces of a given genus modulo the Möbius group a…

2011-06-19abs ↗pdf ↗

Study of Willmore energy on sphere sublevel sets and flow singularities.

problem Understanding the Willmore energy landscape and singularities of the Willmore flow.
method Gluing different instances of the Willmore flow and using an invariant for triple-point-free spheres.
result Classification of initial surfaces with energy at most 12π leading to unavoidable singularities.