Colloquium (2020)

List of colloquium by year
Speaker Taizo Kanenobu (Osaka City University/OCAMI)
Title Study of polynomial invariants of knots
Date MARCH 19 (Fri.) 2021
Place Dept. of Mathematics, Faculty of Science Bldg., E408 & Zoom
Abstract We introduce the study of mathematical theory of knots through polynomial invariants.
Speaker Masaharu Nishio(Osaka City University/OCAMI)
Title Biparabolic Bloch spaces
Date MARCH 19 (Fri.) 2021
Place Dept. of Mathematics, Faculty of Science Bldg., E408 & Zoom
Abstract We consider some function spaces with respect to an iterated parabolic operator of fractional order on the upper half space. Recalling reproducing properties and the orthogonal projection, we shall discuss dual spaces.
Speaker Sho Ejiri (Osaka University)
Title Iitaka’s conjecture and related problems in positive characteristic
Date DECEMBER 02 (Wed.) 2020
Place Dept. of Mathematics, Faculty of Science Bldg., E408 & Zoom
Abstract A surjective morphism whose general fiber is a variety is called an algebraic fiber space, which is used when we describe a geometric structure of a variety and when we apply properties of low-dimensional varieties. Iitaka proposed a conjecture which predicts that the subadditivity of Kodaira dimension holds for algebraic fiber spaces. In this talk, I will introduce some problems on algebraic fiber spaces related to the above conjecture, and will then survey the recent progress in positive characteristic.
Speaker Mikiya Masuda (Osaka City University/OCAMI)
Title The equivariant Serre problem
Date NOVEMBER 04 (Wed.) 2020,
Award Ceremony of the 2020 MSJ Geometry Prize 16:50～17:00
Special Colloquium 17:00～18:00
Place Dept. of Mathematics, Faculty of Science Bldg., E408 & Zoom
Abstract The equivariant Serre problem Abstract: During my stay at the University of Göttingen in the summer of 1989, I heard from Petrie that Schwarz had found a counterexample to the equivariant Serre problem. We had a seminar to understand the counterexample of Schwarz, and soon we got a new result fortunately.This was a turning point in my research and led me to toric topology later, so it left a strong impression on me. I would like to talk about my memories around that time together with the equivariant Serre problem.
Speaker Masahito Ohta (Tokyo University of Science)
Title Relations between unstable standing waves and blowup solutions for nonlinear Schrodinger equations
Date OCTOBER 28 (Wed.) 2020, 17:00～18:00
Place Dept. of Mathematics, Faculty of Science Bldg., E408 & Zoom
Abstract In a situation where the dispersion and the nonlinearity are balanced, stable standing wave solutions exist for nonlinear Schrodinger equations, but if the balance is lost, some standing waves may become unstable. That is, if the standing wave is perturbed, it may exit from a neighborhood of the standing wave. However, in general, it is difficult to investigate the behavior of the solution after exiting from the neighborhood. In addition, in a situation where the nonlinearity is stronger than the dispersion, finite time blowup solutions may exist, so it is expected that some solutions will blow up in a finite time after exiting from a neighborhood of unstable standing wave. In this talk, some known results and recent progress on this issue will be presented.
Speaker Tatsuya Horiguchi (OCAMI)
Title Topics on Hessenberg varieties
Date OCTOBER 7 (Wed.) 2020, 17:00～18:00
Place Dept. of Mathematics, Faculty of Science Bldg., E408 & Zoom
Abstract Hessenberg varieties are subvarieties of flag varieties. Recently, it turned out that their topology make connections with other research areas, such as hyperplane arrangements and graph theory. In this talk, I will explain their connections and a recent result.
Speaker Hideaki Sunagawa (Osaka City University)
Title On the commuting vector fields method for nonlinear wave equations
Date JULY 8 (Wed.) 2020, 17:00～18:00
Place Dept. of Mathematics, Faculty of Science Bldg., E408 & Zoom
Abstract The commuting vector fileds method, originated by F.John and S.Klainerman in 1980's, is a useful tool in study of long-time behavior of solutions to nonlienar wave equations. In this talk we will give a review on basic ideas of this method. Some of its applications and the recent progress will be also presented.
Last Modified on 2021. 03. 05