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Information on mathematics and mathematicians in Japan

TMU GEOMETRY GROUP BULLETIN BOARD

TMU GEOMETRY SEMINAR

Web page of TMU Geometry seminar is available.

Speaker: Ryuma Orita (Tokyo Metropolitan University)

Title: Disjoint superheavy subsets and fragmentation norms

Date & Time: Friday, April 13th, 16:30-

Place: Room 8-618

Abstract: We discuss how the group of Hamiltonian diffeomorphisms of a closed symplectic manifold is "large". Here we consider the fragmentation norm on the group. Brandenbursky showed that the diameter of the group of Hamiltonian diffeomorphisms of a closed Riemman surface of genus greater than 1 is infinite. He used Polterovich's quasi-morphisms for the proof. In this talk, we generalize his result by using spectral invariants derived from Lagrangian Floer theory. This is a joint work with Mormichi Kawasaki.Speaker: Shigehiro Sakata (Miyazaki University)

Title: Symmetry of a triangle and critical points of Riesz potentials

Date & Time: Friday, March 16th, 16:30-

Place: Room 8-618

Abstract: We consider the characterization of regular triangles. In Euclidean geometry, it is well-known that if at least two of the centroid, the incenter and the circumcenter of a triangle coincide, then the triangle has to be regular. In 2012, O'Hara showed that the centroid, the incenter and the circumcenter of a body (the closure of a bounded open set) are obtained as a critical point of a Riesz potential. In other words, critical points of Riesz potentials of a body can be regarded as "centers" of the body. Using critical points of a Riesz potential of a triangle, we derive a sufficient condition for that the triangle has to be regular.Speaker: Atsumu Sasaki (Tokai University)

Title: A Cartan decomposition for spherical homogeneous spaces of reductive type

Date & Time: Friday, January 26th, 16:30-

Place: Room 8-618Speaker: Jérôme Bertrand (Université Toulouse III)

Title: Prescribing the Gauss curvature of convex bodies in the hyperbolic space

Date & Time: Friday, January 19th, 17:00-

Place: Room 8-618

Abstract: I will state and prove an hyperbolic analogue of a classical theorem on Euclidean convex bodies due to Alexandrov. It consists in prescribing the shape of a (pointed) convex body given its Gaussian curvature measure (viewed as a measure on the unit sphere). The existence of such a convex body is based on the study of a non-linear analogue of Kantorovitch's dual problem, a standard tool in optimal mass transport. This is joint work with Philippe Castillon.Speaker:Shouhei Honda (Tohoku University)

Date & Time: Friday, October 6th, 16:30-

Place: Room 8-618Speaker:Shinji Ohno (OCAMI)

Date & Time: Friday, July 28th, 16:30-

Place: Room 8-618Speaker:Tomohiro Fukaya (TMU)

Date & Time: Friday, July 21st, 16:30-

Place: Room 8-618Speaker: Oliver Baues (Georg-August-Universitat Gottingen)

Title: Isometry groups of compact manifolds with indefinite metric

Date & Time: Friday, June 30th, 16:30-

Place: Room 8-618

Abstract: The group of automorphisms of a geometric structure on a compact manifold is a Lie group whose properties are determined to a large degree by the underlying geometry. We consider the question which Lie groups act by isometries on manifolds with indefinite metric. Whereas in the Riemannian case the isometry group acts properly, the isometry groups of indefinite metrics enjoy much greater freedom. In the Lorentzian case, a complete local classification is available for some time now, by work of Adams-Stuck and Zeghib. In this context it is of particular interest to determine the compact homogeneous model spaces for metrics of higher signature. In the talk, we introduce several new results on local and global properties of their full group of isometries.Speaker: Hajime Fujita (Japan Women's University)

Date & Time: Friday, June 23rd, 16:30-

Place: Room 8-618Speaker: Yuichi Ike (The University of Tokyo)

Title: Applications of microlocal sheaf theory to symplectic geometry in cotangent bundles

Date & Time: Friday, June 16th, 16:30-

Place: Room 8-618Speaker: Atsufumi Honda (Yokohama National University)

Title: Isometric immersions with singularities between space forms of the same non-negative curvature

Date & Time: Friday, May 26th, 16:30-

Place: Room 8-618Speaker: Dounnu Sasaki (Waseda University)

Date & Time: Wednesday, May 19th, 16:30-

Place: Room 8-618Speaker: Yoshihiro Sugimoto (RIMS)

Title: Spectral spread and autonomous Hamiltonian diffeomorphisms

Date & Time: Friday, April 28th, 16:30-

Place: Room 8-618Speaker: Yoshiyasu Fukumoto (East China Normal University)

Date & Time: Wednesday, April 26th, 16:30-

Place: Room 8-618Speaker: Hikaru Yamamoto (Tokyo University of Science)

Title: Mean curvature flows in several ambient spaces and its monotonicity formulas

Date & Time: Friday, April 21st, 16:30-

Place: Room 8-618Speaker: Masayuki Aino (Nagoya University)

Title: Riemannian Invariants that Characterize Rotational Symmetries of the Standard Sphere

Date & Time: Friday, April 14th, 16:30-

Place: Room 8-618Speaker: Hiroshi Kawabi (Okayama University)

Title: From non-symmetric random walks on nilpotent covering graphs to distorted Brownian rough paths via discrete geometric analysis

Date & Time: Wednesday, February 1st, 16:30-

Place: Room 8-618Speaker: Tatsuyoshi Hamada (Nihon University)

Title: On star-Ricci flat real hypersurfaces of complex space forms

Date & Time: Friday, January 20th, 16:30-

Place: Room 8-618Speaker: Wilhelm Klingenberg (Durham University)

Title: A global version of a classical theorem of Joachimsthal

Date & Time: Friday, January 13th, 16:30-

Place: Room 8-618Speaker: Reiko Miyaoka (Tohoku University)

Date & Time: Friday, October 28th, 16:30-

Place: Room 8-618Speaker: Motoko Kato (The University of Tokyo)

Title: Embeddings of right-angled Artin groups into higher dimensional Thompson groups

Date & Time: Friday, October 14th, 16:30-

Place: Room 8-618Speaker: Wu Yan (Jiaxing University)

Title: Finite Decomposition complexity of wreath products

Date & Time: Tuesday, August 2nd, 15:00-

Place: Room 8-618Speaker: Shinji Ohno (Osaka City University)

Title: A construction of biharmonic submanifolds in compact symmetric spaces

Date & Time: Friday, July 15th, 16:30-

Place: Room 8-618Speaker: Ryuma Orita (University of Tokyo)

Title: Non-contractible periodic orbits in Hamiltonian dynamics on tori

Date & Time: Friday, June 24th, 16:30-

Place: Room 8-618

Abstract: It is an important problem having its origin in Conley, Salamon and Zehnder's works that what condition leads the existence of infinitely many periodic orbits of Hamiltonian diffeomorphisms on symplectic manifolds. Indeed, at the very beginning, they proved that every (weakly) non-degenerate Hamiltonian diffeomorphism on tori has infinitely many periodic orbits. On the other hand, in the context of non-contractible orbits, Ginzburg and Gurel proved that every Hamiltonian diffeomorphism on atoroidal or toroidally monotone symplectic manifolds has infinitely many (non-contractible) periodic orbits, provided that the diffeomorphism has one non-contractible periodic orbit. Here it is worth pointing out that we cannot apply their theorem for tori, which are not atoroidal or toroidally monotone. In this talk, we show that the presence of one non-contractible periodic orbit on tori yields the existence of infinitely many non-contractible periodic orbits.Speaker: Masato Mimura (Tohoku University)

Title: Strong algebraization of fixed point properties

Date & Time: Friday, June 17th, 16:30-

Place: Room 8-618Speaker: Yohei Sakurai (University of Tsukuba)

Title: Rigidity phenomena in manifolds with boundary under a lower weighted Ricci curvature bound

Date & Time: Friday, June 3rd, 16:30-

Place: Room 8-618Speaker: Kurando Baba (Tokyo University of Science)

Title: The geometry of orbits of the isotropy representations for semisimple pseudo-Riemannian symmetric spaces

Date & Time: Friday, May 27th, 16:30-

Place: Room 8-618Speaker: Hajime Urakawa (Tohoku University)

Title: Rigidity of transversally biharmonic maps between foliated Riemannian manifolds

Date & Time: Friday, May 20th, 16:30-

Place: Room 8-618Speaker: Shin Kikuta (Kogakuin University)

Title: Boundary behavior of complete Kahler-Einstein metric over quasi-projective manifolds with boundary of general type

Date & Time: Friday, May 13th, 16:30-

Place: Room 8-618

Abstract: In this talk, I will discuss a boundary behavior of the complete Kahler-Einstein metric of negative Ricci curvature on a quasi-projective manifold with semiample log-canonical bundle. In particular, I will focus on its relations with degeneration of positivity for the log-canonical bundle on the boundary. Based on a result due to G. Schumacher, I have some natural prediction. I will present it and report that it is actually true in the case when the boundary is of general type.Speaker: Tomohiro Fukaya (Tokyo Metropolitan University)

Title: The coarse Baum-Connes conjecture for product of nonpositive curved spaces and groups

Date & Time: Friday, April 15th, 16:30-

Place: Room 8-618

Abstract: The Baum-Connes conjecture states that the K-theory of a reduced group C^*-algebra for a discrete group is isomorphic to the equivariant K-homology of a universal space for proper actions of the group. The coarse Baum-Connjecture is a gnon-equivarianth version of the conjecture, which states that the K-theory of a certain C^*-algebra constructed from a metric space is isomorphic to the gcoarseh K-homology of the metric space. Now both conjecture is verified for wide classes of groups and metric spaces. In this talk, we explain that the coarse Baum-Connes conjecture holds for a product of hyperbolic groups, CAT(0)-groups, polycyclic groups, and relatively hyperbolic groups satisfying certain conditions. This talk is based on the joint work with Shin-ichi Oguni.Speaker: Jun (Imai) O'Hara (Tokyo Metropolitan University)

Title: Regularization of Riesz energies of submanifolds

Date & Time: Friday, January 8th, 16:30-

Place: Room 8-618

Abstract: I will talk on some geometric quantities for knots, surfaces, and compact submanifolds with boundaries which we can obtain by regularizin Riesz energy using either Hadamard regularization or analytic continuation. (joint work with Gil Solanes (Universitat Autonoma de Barcelona))Speaker: Jochen Bruening (Humboldt-Universitat zu Berlin)

Title: Global analysis on Thom-Mather stratified spaces

Date & Time: Friday, December 11th, 16:30-

Place: Room 8-618Speaker: Hokuto Konno (University of Tokyo)

Title: Bounds on genus and configurations of embedded surfaces in 4-manifolds

Date & Time: Friday, November 13th, 16:30-

Place: Room 8-618Speaker: Kotaro Kawai (University of Tokyo)

Title: Cohomogeneity one coassociative submanifolds

Date & Time: Friday, October 30th, 16:30-

Place: Room 8-618Speaker: Kota Hattori (Keio University)

Title: On special Lagrangian submanifolds embedded in hyperKahler manifolds

Date & Time: Friday, Octover 16th, 16:30-

Place: Room 8-618Speaker: Ayato Mitsuishi (Tohoku University)

Title: Good coverings of Alexandrov spaces

Date & Time: Friday, Octover 9th, 16:30-

Place: Room 8-618Speaker: Shohei Honda (Tohoku University)

Title: Elliptic PDEs on compact Ricci limit spaces and applications

Date & Time: Friday, July 31st, 16:30-

Place: Room 8-618Speaker: Naoki Katou (University of Tokyo)

Title: Classification of solvable Lie flows of codimension 3

Date & Time: Friday, July 31st, 16:30-

Place: Room 8-618Speaker: Shigehiro Sakata (Waseda University)

Title: Every convex body has a unique illuminating center

Date & Time: Friday, July 31st, 15:00-16:30

Place: Room 8-618

Speaker: Masaro Takahashi (Kurume National College of Technology)

Title: Holomorphic isometric embeddings of the projective line into quadrics

Date & Time: Friday, July 17th, 16:30-

Place: Room 8-618

Speaker: Suguru Ishikawa (Kyoto University, RIMS)

Title: Spectral invariants of distance functions

Date & Time: Friday, July 10th, 16:30-

Place: Room 8-618

Abstract: Entov and Polterovich have introduced the notion of the (super) heaviness of a closed subset of a symplecitic manifold. A superheavy subset cannot be displaced by symplectic isotopy, and a heavy subset cannot be displaced by Hamiltonian isotopy. An important property is that (super)heaviness is preserved by the product, which enabled them to find a lot of examples of non-displaceable subsets. (Super)heaviness is defined by using the spectral invariants of the Floer homology. Calculating the spectral invariants of Floer homology of distance-like functions, we recently found some kind of superheavy subsets in symplectic manifolds. We showed that if convex open subsets in Euclidean space with the standard symplectic form are disjointly embedded in a spherically negative monotone closed symplectic manifold, their compliment is superheavy. The key of the proof is the estimate of the Conley-Zhender index of the periodic orbits of the special Hamiltonian. This method can also be applied to spherically monotone symplectic manifolds, by which we can show an analogous property of the spherically monotone symplectic manifolds.

TMU GEOMETRY SPECIAL SEMINAR

Speaker: Franz Pedit (UMass Amherst)

Date & Time: Saturday, March 11th, 11:00--15:00

Place: Room 8-61011:00--12:00 1st lecture

Title: Towards a constrained Willmore conjecture

Abstract: The constrained Willmore problem investigates the minimizers, and more generally the critical points, of the Willmore functional (bending energy) on immersions of surfaces under variations preserving the conformal type of the surface. We give a brief introduction/overview of the topic and discuss a number of conjectures, together with supporting evidence, which have emerged over the past years. Ramifications of those conjectures would greatly enhance our understanding of the Willmore functional on the space of conformal immersions of compact Riemann surfaces.12:00--14:00 lunch and discussion

14:00--15:00 2nd lecture

Title: Energy quantization for harmonic 2-spheres in non-compact symmetric spaces

Abstract: It is well known from results by Uhlenbeck, Chern-Wolfson and Burstall-Rawnsley that harmonic 2-spheres in compact symmetric spaces have quantized energies. Using the reformulation of the harmonic map equation as a family of flat connections, we construct an energy preserving duality between harmonic maps from non-compact symmetric spaces into their compact duals. Applying this construction to the conformal Gauss maps of Willmore 2-spheres in the n-sphere provides a generalization and unifying approach to existing quantization results in special cases: Bryant for n=3; Montiel for n=4; and Ejiri for Willmore 2-spheres admitting a dual Willmore surface.

List of earlier geometry seminars (since October 2003)

CONFERENCE NEWS

TMU-RELATED AND TOKYO AREA CONFERENCES

GEOMETRY SEMINARS IN THE TOKYO AREA

OCAMI Osaka City University Advanced Mathematical Institute

GEOMETRY (AND MATHEMATICS IN GENERAL) IN JAPAN

MATHEMATICAL SOCIETY OF JAPAN

Home page of the Mathematical Society of Japan (information in English on membership, meetings, journals and other publications, and the history and structure of the MSJ)

Home page of the Geometry Section of the MSJ ( provisional English version)

JAPANESE UNIVERSITIES AND OTHER ORGANISATIONS IN JAPAN

Mathematics Department servers in Japanese universities (many have "access maps" and other useful information)

Another list of department web pages in English

Japan Society for the Promotion of Science (JSPS) (including information on research grants and fellowships)

GUIDE TO THIS WEB SITE

Much of the information on this web site is geared towards researchers, but, depending on your mathematical background, you should be able to find something of interest, whether you are interested in the Japanese system or mathematics in general.

Web sites of Japanese universities A list of English-language web sites for the mathematics departments of universities in Japan. From these you can navigate to the main web sites of each university. The quantity and quality of information is variable, but you can get some idea of what Japanese universities are like.

Japan[Rochester Visiting Scholar Program (Japanese)

INFORMATION ON STUDYING IN JAPAN

There are still relatively few foreign students, and even fewer foreign students studying mathematics, at Japanese universities. However, the major universities welcome such students, and provide stimulating environments for study and research, and generous scholarships are available through the Japanese Government. If you are interested in continuing your studies in Japan, click here for more information.