Benjamin McKay
We construct an explicit diffeomorphism taking any fibration of a sphere by great circles into the Hopf fibration, using elementary geometry--indeed the diffeomorphism is a local (differential) invariant, algebraic in derivatives.
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Blaschke Conjecture and Complex Geometry
本文通过引入大二次曲面纤维化，结合bend-and-break论证与Hwang-Mok VMRT识别，证明了在切丛具有适配复结构条件下Blaschke猜想成立。
It is shown that analytic conformal submersions of $S^3$ are given by intersections of (not necessary closed) complex surfaces with a quadratic real hyper-surface in $\mathbb{C}P^3.$ A new description of the space of circles in the 3-sphere in terms of a natural bilinear form on the tangent sphere bundle of $S^3$ is given. As an application it is shown that every conformal fibration of $S^3$ by circles is the Hopf fibration up to conformal transformations.
We investigate Gauss maps associated to great circle fibrations of $S^3$. We show that the associated Gauss map to such a fibration is harmonic (respectively minimal) if and only if the unit vector field generating the great circle foliation is harmonic (respectively minimal). These results can be viewed as analogues of the classical theorem of Ruh and Vilms about the harmonicity of the Gauss map of a minimal submanifold in the euclidean space. Moreover, we prove that a harmonic or minimal unit vector field in $S^3$ with great circle integral curves is a Hopf vector field.
Great Circle Fibrations and Contact Structures on Odd-Dimensional Spheres
本文证明从5-球面开始，所有奇数维球面都存在与纤维正交的超平面分布非切触结构的光滑大圆纤维化，打破了3-球面中的已知结论。
Heinz Hopf's famous fibrations of the 2n+1-sphere by great circles, the 4n+3-sphere by great 3-spheres, and the 15-sphere by great 7-spheres have a number of interesting properties. Besides providing the first examples of homotopically nontrivial maps from one sphere to another sphere of lower dimension, they all share two striking features: (1) Their fibers are parallel, in the sense that any two fibers are a constant distance apart, and (2) The fibrations are highly symmetric. For example, there is a fiber-preserving isometry of each total space which takes any given fiber to any other one. …
In a 1983 paper with Frank Warner, we proved that the space of all great circle fibrations of the 3-sphere S^3 deformation retracts to the subspace of Hopf fibrations, and so has the homotopy type of a pair of disjoint two-spheres. Since that time, no generalization of this result to higher dimensions has been found, and so we narrow our sights here and show that in an infinitesimal sense explained below, the space of all smooth oriented great circle fibrations of the 2n+1 sphere S^(2n+1) deformation retracts to its subspace of Hopf fibrations. The tools gathered to prove this also serve to sh…
Given any smooth fibration of the unit 3-sphere by great circles, we show that the distribution of 2-planes orthogonal to the great circle fibres is a tight contact structure, a fact well known in the special case of the Hopf fibrations. The proof expresses hypothesis and conclusion as differential inequalities involving functions on disks transverse to the fibres, and shows that one inequality implies the other.
We investigate the maximal solid tubes around short simple geodesics in hyperbolic three-manifolds and how complex length of curves relate to closed, incompressible, least area minimal surfaces. As applications, we prove, there are some closed hyperbolic three-manifolds fibering over the circle which are not foliated by closed incompressible minimal surfaces diffeomorphic to the fiber. We also show, the existence of quasi-Fuchsian manifolds containing arbitrarily many embedded closed incompressible minimal surfaces. Our strategy is to prove main theorems under natural geometric conditions on t…
In this paper we classify symplectic Lefschetz fibrations (with empty base locus) on a four-manifold which is the product of a three-manifold with a circle. This result provides further evidence in support of the following conjecture regarding symplectic structures on such a four-manifold: if the product of a three-manifold with a circle admits a symplectic structure, then the three-manifold must fiber over a circle, and up to a self-diffeomorphism of the four-manifold, the symplectic structure is deformation equivalent to the canonical symplectic structure determined by the fibration of the t…
A fibration of a Riemannian manifold is fiberwise homogeneous if there are isometries of the manifold onto itself, taking any given fiber to any other one, and preserving fibers. Examples are fibrations of Euclidean n-space by parallel n-planes, and the Hopf fibrations of the round n-sphere by great n-spheres. In this paper, we describe all the fiberwise homogeneous fibrations of Euclidean and hyperbolic 3-space by geodesics. Our main result is that, up to fiber-preserving isometries, there is precisely a one-parameter family of such fibrations of Euclidean 3-space, and a two-parameter family …
Analytic diffeomorphisms of the circle and topological Riemann-Roch theorem for circle fibrations
本文通过构造圆圈的解析微分同胚群的中心扩张，推导出新的拓扑Riemann-Roch定理，用于复线丛在圆纤维化上的应用。
We list all analytic diffeomorphisms between an open subset of the 4-dimensional projective space and an open subset of the 4-dimensional sphere that take all line segments to arcs of round circles. These are the following: restrictions of the quaternionic Hopf fibrations and projections from a hyperplane to a sphere from some point. We prove this by finding the exact solutions of the corresponding system of partial differential equations.
On extending results of Gluck and Warner on fibrations of spheres by great subspheres
本文基于Gluck和Warner 1983年的研究，探讨如何将他们的结果推广到更高维球面，分析Hopf纤维化在纤维上一致性的条件及限制。
Synthetic construction of the Hopf fibration in a double orthogonal projection of 4-space
本文通过四维空间的双正交投影方法，合成构造了3球面的纤维，展示了2球面点对应的纤维结构及嵌套环面的可视化。
Homotopy Type of the Space of Fibrations of the Three-sphere by Simple Closed Curves
本研究确定了三维球面简单闭曲线光滑纤维化模空间的同伦型，证明其与Hopf纤维化子空间同伦型一致，还刻画了该模空间的Fréchet流形结构与建模空间。
Relative analytic reciprocity laws
本文研究复线束在圆定向纤维上的互易定律，证明了特定条件下相关上同调群的和为零。
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