## 談話会（2016年度）

日時 4月13日(水) 16:30～17:30 濱野 佐知子（大阪市立大学大学院理学研究科） Variational formulas for hydrodynamic differentials and the application (流体力学的微分の変分公式とその応用について) 数学大講究室 (理学部棟E408) For a fixed open Riemann surface $R$ of genus one, we shall consider the set $\mathcal C$ of closings of $R$. M. Shiba showed that the set $\mathfrak M$ of moduli of $\mathcal C$ is a closed disk in $\mathbb H$. In this talk, we shall consider the deforming open torus $R(t)$ with complex parameter $t$, and show the close relation between the Euclidean diameter of the moduli disk $\mathfrak M(t)$ of $R(t)$ and pseudoconvexity. The key of the proof is the variational formulas for hydrodynamic differentials.
日時 5月11日(水) 16:30～17:30 Seonjeong Park （OCAMI） Cohomological rigidity problems in toric topology 数学大講究室 (理学部棟E408) One of most important topological invariants is a (co)homology. In general, (co)homology is not strong enough to determine the topological type. But in toric topology, cohomology can be a strong topological invariant. In many cases, the cohomology ring of a smooth manifold with a nice toric action can determine the topological type of the manifold. In this talk, I will introduce various kinds of cohomological rigidity problems in toric topology and give some results which support the affirmative answer to the cohomological rigidity problems.