Information on mathematics and mathematicians in Japan


TMU contact information


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 8-618

Speaker: 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 8-618

Speaker:Shinji Ohno (OCAMI)
Date & Time: Friday, July 28th, 16:30-
Place: Room 8-618

Speaker:Tomohiro Fukaya (TMU)
Date & Time: Friday, July 21st, 16:30-
Place: Room 8-618

Speaker: 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 8-618

Speaker: 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 8-618

Speaker: 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 8-618

Speaker: Dounnu Sasaki (Waseda University)
Date & Time: Wednesday, May 19th, 16:30-
Place: Room 8-618

Speaker: Yoshihiro Sugimoto (RIMS)
Title: Spectral spread and autonomous Hamiltonian diffeomorphisms
Date & Time: Friday, April 28th, 16:30-
Place: Room 8-618

Speaker: Yoshiyasu Fukumoto (East China Normal University)
Date & Time: Wednesday, April 26th, 16:30-
Place: Room 8-618

Speaker: 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 8-618

Speaker: Masayuki Aino (Nagoya University)
Title: Riemannian Invariants that Characterize Rotational Symmetries of the Standard Sphere
Date & Time: Friday, April 14th, 16:30-
Place: Room 8-618

Speaker: 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 8-618

Speaker: Tatsuyoshi Hamada (Nihon University)
Title: On star-Ricci flat real hypersurfaces of complex space forms
Date & Time: Friday, January 20th, 16:30-
Place: Room 8-618

Speaker: Wilhelm Klingenberg (Durham University)
Title: A global version of a classical theorem of Joachimsthal
Date & Time: Friday, January 13th, 16:30-
Place: Room 8-618

Speaker: Reiko Miyaoka (Tohoku University)
Date & Time: Friday, October 28th, 16:30-
Place: Room 8-618

Speaker: 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 8-618

Speaker: Wu Yan (Jiaxing University)
Title: Finite Decomposition complexity of wreath products
Date & Time: Tuesday, August 2nd, 15:00-
Place: Room 8-618

Speaker: Shinji Ohno (Osaka City University)
Title: A construction of biharmonic submanifolds in compact symmetric spaces
Date & Time: Friday, July 15th, 16:30-
Place: Room 8-618

Speaker: 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 8-618

Speaker: 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 8-618

Speaker: 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 8-618

Speaker: Hajime Urakawa (Tohoku University)
Title: Rigidity of transversally biharmonic maps between foliated Riemannian manifolds
Date & Time: Friday, May 20th, 16:30-
Place: Room 8-618

Speaker: 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-equivarianth version of the conjecture, which states that the K-theory of a certain C^*-algebra constructed from a metric space is isomorphic to the gcoarseh 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 8-618

Speaker: 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 8-618

Speaker: Kotaro Kawai (University of Tokyo)
Title: Cohomogeneity one coassociative submanifolds
Date & Time: Friday, October 30th, 16:30-
Place: Room 8-618

Speaker: Kota Hattori (Keio University)
Title: On special Lagrangian submanifolds embedded in hyperKahler manifolds
Date & Time: Friday, Octover 16th, 16:30-
Place: Room 8-618

Speaker: Ayato Mitsuishi (Tohoku University)
Title: Good coverings of Alexandrov spaces
Date & Time: Friday, Octover 9th, 16:30-
Place: Room 8-618

Speaker: Shohei Honda (Tohoku University)
Title: Elliptic PDEs on compact Ricci limit spaces and applications
Date & Time: Friday, July 31st, 16:30-
Place: Room 8-618

Speaker: Naoki Katou (University of Tokyo)
Title: Classification of solvable Lie flows of codimension 3
Date & Time: Friday, July 31st, 16:30-
Place: Room 8-618

Speaker: 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.


Speaker: Franz Pedit (UMass Amherst)
Date & Time: Saturday, March 11th, 11:00--15:00
Place: Room 8-610

11:00--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)




OCAMI Osaka City University Advanced Mathematical Institute



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)


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)



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)


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.