東大作用素環セミナー

今後の予定

• 2026年6月9日（火）16時45分～18時15分 数理科学研究棟126号室

  • 講演者：星野泰佑（東大数理）

  • 題目：Rigidity for graph-wreath product II1 factors 

  • アブストラクト：Given a graph C=(V,E) and a family of vertex groups (Gv) indexed by the set of vertices V, their graph product group GC is the free product of (Gv), subject to the condition that elements from adjacent vertex groups commute. Then, the graph-wreath product group, a variant of graph product construction, is defined to be the semidirect product of a certain Bernoulli-type action on a graph product group. The rigidity problem for these constructions concerns how much information of the original graph or vertex groups remains in the group von Neumann algebras of their graph product or graph-wreath product groups. In this talk, we will review the recent progress on this topic and introduce our rigidity type results for graph-wreath product groups. We make use of the notion of bi-exactness by Ozawa for the proof. 

• 2026年6月16日（火）16時45分～18時15分 数理科学研究棟126号室

  • 講演者：石倉宙樹（京大数理研）

  • 題目：Borel planar complexes and soficity 

• 2026年6月23日（火）16時45分～18時15分 数理科学研究棟126号室

  • 講演者：Ravi Mistry（東大数理）

  • 題目：未定

• 2026年7月7日（火）16時45分～18時15分 数理科学研究棟126号室

  • 講演者：橋本七海（慶応大）

  • 題目：Equivalence of categories of KK-theory or E-theory for C*-algebras over topological spaces by reflection functors 

• 2026年7月14日（火）16時45分～18時15分 数理科学研究棟126号室

  • 講演者：安藤浩志（千葉大）

  • 題目：

• 2026年7月21日（火）16時45分～18時15分 数理科学研究棟126号室

  • 講演者：磯野優介（京大数理研）

  • 題目：Introduction to Tomita--Takesaki theory 

  • アブストラクト：In this talk, we give an introduction to Tomita--Takesaki theory, which plays a central role in the study of type III von Neumann algebras. The talk assumes no prior knowledge of the theory and begins with tracial von Neumann algebras. We discuss the difficulties that arise in the non-tracial setting and introduce the modular automorphism group and modular conjugation associated with a faithful normal state. As a concrete class of examples, we consider Powers--Araki--Woods factors and illustrate how the abstract definitions can be made explicit. Finally, we briefly touch on more structural notions such as the KMS condition, the continuous core, and Connes' invariants, and explain the importance of Tomita--Takesaki theory in the study of type III factors.

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