ICTS

We will discuss $\rho$-equivariant conformal minimal immersions of finite energy into $\mathbb{CH}^2$. We prove that the induced metric is complete at a puncture $p$ if and only if the holonomy of $\rho$ around $p$ is parabolic. In this case $f$ is proper and $\partial f$ has pole at each puncture, so on the compactification $\Sigma$ we obtain a parabolic $\mathrm{PU}(2,1)$–Higgs bundle $(E,\Phi)$ with nilpotent residues and zero parabolic weights. This yields an Osserman-type extension principle for minimal surfaces in $\mathbb{CH}^2$ with complete ends. We further provide an algebro–geometric characterization of these immersions in terms of their associated parabolic Higgs data. This is a joint work with Indranil Biswas and John Loftin.

In this talk, I will discuss the existence of a one-parameter family of infinite genus maxfaces exhibiting infinitely many planar spacelike ends.

In this talk, first we will show that for every spacelike CMC surface of revolution (except spacelike cylinders and standard hyperboloids) about a timelike axis or spacelike axis, which is either an unduloid or a nodoid, in the Lorentz-Minkowski space L^3 there is an associated Weierstrass-P function. Next, using this association, we will show that unduloid and nodoid cannot be algebraic. A similar result is obtained for CMC surfaces of revolution in the Euclidean space E^3.

I shall consider minimal hypersurfaces inside the unit ball whose boundary on the sphere is a small perturbation of the link of a minimizing quadratic cone. In this talk, I will discuss a recent result where I show that such minimal surfaces are uniquely determined by their boundary condition. In particular the solutions of the Plateau problem are unique for boundary conditions given by small perturbations of the link of a quadratic cone. Building on previous results we can characterize these unique surfaces. This is a joint work with Gábor Székelyhidi.

We will give an introduction to our recent joint work with Otis Chodosh, Christos Mantoulidis and Zhihan Wang on generic regularity for area minimizing hypersurfaces up to dimension 11.

Harmonic maps to symmetric spaces are used in the non-Abelian Hodge correspondence to bridge surface group representations with Higgs bundles. In special cases, these harmonic maps are conformal and hence give minimal surfaces in a symmetric space. In the first lecture, we look at the case of SL(3,R) and describe some asymptotics via Blaschke metrics.

In the second lecture, we will look at higher genus minimal Lagrangians in CP^2. There will be objects reminiscent of Higgs bundles, but which are not Higgs bundles. This will involve loop group methods and satisfying a closing condition.

We prove the existence of complete minimal surfaces in $\mathbb{R}^3$ of arbitrary genus $p\, >\, 1$ and least absolute curvature with precisely two ends --- one catenoidal and one Enneper-type --- thereby resolving, affirmatively, a conjecture posed by Weber. These surfaces, which are called \emph{Angel surfaces}, generalize the genus-one example constructed earlier by Fujimori and Shoda. We extend the orthodisk method developed by Weber and Wolf, \cite{weber2002teichmuller}, to construct the minimal surfaces. A central idea in our construction is the notion of \emph{partial symmetry}, which enables us to introduce controlled symmetry into the surface. Reference: [Weber and Wolf(2002)] Matthias Weber and Michael Wolf. Teichm¨uller theory and handle addition for minimal surfaces. Annals of mathematics, pages 713–795, 2002.

We describe the asymptotics of high energy harmonic maps from Riemann surfaces to locally symmetric spaces in special classes in two settings: surface group actions on PSL(2,\R) and on SL(3,\R).  The goal is to highlight some aspects of technique, though inevitably we will state some results that follow from the methods. Joint work with Dumas, Loftin, Tamburelli, and Pan, if not others.

Harmonic maps to symmetric spaces are used in the non-Abelian Hodge correspondence to bridge surface group representations with Higgs bundles. In special cases, these harmonic maps are conformal and hence give minimal surfaces in a symmetric space. In the first lecture, we look at the case of SL(3,R) and describe some asymptotics via Blaschke metrics.

In the second lecture, we will look at higher genus minimal Lagrangians in CP^2. There will be objects reminiscent of Higgs bundles, but which are not Higgs bundles. This will involve loop group methods and satisfying a closing condition.

Maximal surfaces in 3-dimensional Lorentz-Minkowski space arise as solutions to the variational problem of local area maximizing among the spacelike surfaces. These surfaces are zero mean curvature surfaces, and maximal surfaces with singularities are called generalized maximal surfaces. Maxfaces are a special class of these generalized maximal surfaces where singularities appear at points where the tangent plane contains a light-like vector. I will present the construction of a new family of maxfaces of high genus that are embedded outside a compact set and have arbitrarily many catenoid or planar ends using the node opening technique. The surfaces look like spacelike planes connected by small necks. Among the examples are maxfaces of the Costa-Hoffman-Meeks type. More specifically, the singular set form curves around the waists of the necks. In generic and some symmetric cases, all but finitely many singularities are cuspidal edges, and the non-cuspidal singularities are swallowtails evenly distributed along the singular curves. This work is conducted in collaboration with Dr. Hao Chen, Dr. Anu Dhochak, and Dr. Pradip Kumar.

For a closed Riemann surface X, and an irreducible representation R from the fundamental group of X to PSL(2,C), a seminal theorem of Donaldson proves the existence of an R-equivariant harmonic map from the universal cover of X into hyperbolic 3-space. We shall discuss a generalization of this result to the case when X is a punctured Riemann surface arising from an element of the enhanced Teichmüller space, and R is a framed PSL(2,C)-representation. Our technique involves the harmonic map heat flow, and the relation between the asymptotic behaviour of a harmonic map and the singular-flat geometry of its Hopf differential. This is joint work with Gobinda Sau. 

Discrete minimal surfaces in the Euclidean space are central in the research field discrete differential geometry. Similarly, we can consider discrete spacelike maximal surfaces and discrete timelike minimal surfaces in Lorentz-Minkowski space. Although their formulation is analogous to discrete minimal surfaces, their behaviors are quite different.

In this talk we introduce recent progress on discrete zero mean curvature surfaces in Euclidean and Lorentz-Minkowski spaces. After briefly introducing basic results on discrete minimal surfaces, we investigate discrete zero mean curvature surfaces in Lorentz-Minkowski space and their singular behaviors. Furthermore, if time permits, we will introduce a construction of discrete zero mean curvature surfaces in Lorentz-Minkowski space that change causal characters along specific singularities.

This talk is partially based on ongoing project with Joseph Cho, Wayne Rossman, and Seong-Deog Yang.

There is a broad body of work devoted to proving theorems of the following form: spaces with infinitely many special sub-spaces are either nonexistent or rare. Such finiteness statements are important in algebraic geometry, number theory, and the theory of moduli space and locally symmetric spaces. I will talk about joint work with Simion Filip and David Fisher proving a finiteness statement of this kind in a differential geometry setting. Our main theorem is that a closed negatively curved analytic Riemannian manifold with infinitely many closed totally geodesic hypersurfaces must be isometric to an arithmetic hyperbolic manifold. The talk will be more focused on providing background and context than details of proofs and should be accessible to a general audience.

Complete minimal surfaces in R^3 have been much studied but much less is known about R^4. I will recall the main tools in R^4 and give a couple of examples of minimal embeddings of the complex plane in R^4. Then I will focus on complete minimal tori of curvature -8π and one end: in R^3 there is a unique example (the Chen-Gackstetter square torus) but in R^4 we can construct examples on all the rectangular tori. I will discuss the strategy for the construction and indicate the many questions which remain open. Joint work with Marc Soret.

We discuss the topological realization problem for minimally embedding compact surfaces in round spheres and balls. In 1970, using the solution to the Plateau problem, Lawson constructed orientable minimal surfaces of each genus embedded in $S^3$. In recent work with Karpukhin, McGrath and Stern, using equivariant eigenvalue optimization methods and a priori eigenspace dimension bounds, we constructed orientable free boundary minimal surfaces in $B^3$ of any genus and (positive) number of boundary, components. Now we have extended our methods to handle the nonorientable case, constructing embedded minimal surfaces in $S^4$ diffeomorphic to the connect-sum of any number of real projective planes: these all have area (so Willmore bending energy) under $8\pi$ and enjoy other interesting geometric features. The analogous construction for nonorientable free boundary minimal surfaces embedded in $B^4$ looms on the horizon. Open problems and speculation about potential discretizations may be offered if time permits....

Further applications: Alexandrov Theorem and Serrin Theorem.