## Operator Algebra Seminars

Seminar information archive ～12/01｜Next seminar｜Future seminars 12/02～

Date, time & place | Wednesday 16:30 - 18:00 122Room #122 (Graduate School of Math. Sci. Bldg.) |
---|

**Seminar information archive**

### 2011/01/11

16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Noncommutative geometry and diffeomorphism-invariant geometries (ENGLISH)

**Raphael Ponge**(Univ. Tokyo)Noncommutative geometry and diffeomorphism-invariant geometries (ENGLISH)

### 2010/12/16

16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Evolution of Quantum Dynamical Systems (ENGLISH)

**Marco Merkli**(Memorial Univ. Newfoundland)Evolution of Quantum Dynamical Systems (ENGLISH)

### 2010/12/16

15:15-16:15 Room #122 (Graduate School of Math. Sci. Bldg.)

Fixed point theorems and derivations (ENGLISH)

**Nicolas Monod**(EPFL)Fixed point theorems and derivations (ENGLISH)

### 2010/12/09

16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Spectral flow associated to KMS states with periodic KMS group action (ENGLISH)

**Ryszard Nest**(Univ. Copenhagen)Spectral flow associated to KMS states with periodic KMS group action (ENGLISH)

### 2010/11/30

16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Noncommutative geometry and Rankin-Cohen brackets (ENGLISH)

**Yi-Jun Yao**(Fudan Univ.)Noncommutative geometry and Rankin-Cohen brackets (ENGLISH)

### 2010/11/25

16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Classification of actions of Kac algebras (JAPANESE)

**Reiji Tomatsu**(Tokyo Univ. Science)Classification of actions of Kac algebras (JAPANESE)

### 2010/11/18

16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Perturbation of dual operator algebras and similarity (ENGLISH)

**Jean Roydor**(Univ. Tokyo)Perturbation of dual operator algebras and similarity (ENGLISH)

### 2010/11/04

16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Nonequilibrium Statistical Mechanics (JAPANESE)

**Yoshiko Ogata**(Univ.Tokyo)Nonequilibrium Statistical Mechanics (JAPANESE)

### 2010/10/28

16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Type III representations of the infinite symmetric group (ENGLISH)

**Makoto Yamashita**(Univ. Tokyo)Type III representations of the infinite symmetric group (ENGLISH)

[ Abstract ]

Based on earlier results about the structure of the II$_1$ representations of the infinite symmetric group, we investigate its type III representations and the related inclusion of von Neumann algebras of type III.

Based on earlier results about the structure of the II$_1$ representations of the infinite symmetric group, we investigate its type III representations and the related inclusion of von Neumann algebras of type III.

### 2010/10/21

16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Free probability and entropy additivity problems for Quantum information theory (ENGLISH)

**Benoit Collins**(Univ. Ottawa)Free probability and entropy additivity problems for Quantum information theory (ENGLISH)

### 2010/10/14

16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Nonstandard analysis for operator algebraists (JAPANESE)

**Yasuyuki Kawahigashi**(Univ. Tokyo)Nonstandard analysis for operator algebraists (JAPANESE)

### 2010/07/22

16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)

$W^*$ Rigidity for actions of wreath product groups (ENGLISH)

**Owen Sizemore**(UCLA)$W^*$ Rigidity for actions of wreath product groups (ENGLISH)

[ Abstract ]

The past 8 years have seen much progress in the classification of

actions of groups on measure spaces. Much of this is due to new powerful

techniques in operator algebras. We will survey some of these results

as well as the new operator algebra techniques. We will then give new

results concerning the classification of actions of wreath product groups.

The past 8 years have seen much progress in the classification of

actions of groups on measure spaces. Much of this is due to new powerful

techniques in operator algebras. We will survey some of these results

as well as the new operator algebra techniques. We will then give new

results concerning the classification of actions of wreath product groups.

### 2010/07/15

16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Type II$_1$ von Neumann representations for Hecke operators on Maass forms (after F. Radulescu) (ENGLISH)

**Narutaka Ozawa**(Univ. Tokyo)Type II$_1$ von Neumann representations for Hecke operators on Maass forms (after F. Radulescu) (ENGLISH)

### 2010/07/08

16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Killing weeds with annular multiplicities $*10$ via quadratic tangles (ENGLISH)

**Dave Penneys**(UC Berkeley)Killing weeds with annular multiplicities $*10$ via quadratic tangles (ENGLISH)

[ Abstract ]

In recent work with Morrison, Peters, and Snyder, we eliminate two

families of possible principal graphs with graph norms less than 5 using

techniques derived from Jones' work on quadratic tangles.

In recent work with Morrison, Peters, and Snyder, we eliminate two

families of possible principal graphs with graph norms less than 5 using

techniques derived from Jones' work on quadratic tangles.

### 2010/07/06

16:30-18:00 Room #118 (Graduate School of Math. Sci. Bldg.)

On the Existence of the Dynamics for Anharmonic Quantum Oscillator Systems (ENGLISH)

**Robert Sims**(Univ. Arizona)On the Existence of the Dynamics for Anharmonic Quantum Oscillator Systems (ENGLISH)

### 2010/06/24

16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Strong solidity of factors from lattices in SO(n,1) and SU(n,1) (ENGLISH)

**Thomas Sinclair**(Vanderbilt Univ.)Strong solidity of factors from lattices in SO(n,1) and SU(n,1) (ENGLISH)

[ Abstract ]

Generalizing techniques found in Ozawa and Popa,

``On a class of II$_1$ factors with at most one Cartan subalgebra, II''

(Amer. J. Math., to appear), we show that the group factors of ICC

lattices in SO(n,1) and SU(n,1), $n\\ge2$, are strongly solid. If

time permits, we will also discuss applications to $L^2$-rigidity.

Generalizing techniques found in Ozawa and Popa,

``On a class of II$_1$ factors with at most one Cartan subalgebra, II''

(Amer. J. Math., to appear), we show that the group factors of ICC

lattices in SO(n,1) and SU(n,1), $n\\ge2$, are strongly solid. If

time permits, we will also discuss applications to $L^2$-rigidity.

### 2010/06/17

16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)

On a relative version of Wall's conjecture (ENGLISH)

**Feng Xu**(UC Riverside)On a relative version of Wall's conjecture (ENGLISH)

### 2010/06/10

16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Random groups and nonarchimedean lattices (JAPANESE)

**Mikael Pichot**(IPMU)Random groups and nonarchimedean lattices (JAPANESE)

### 2010/06/03

16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Fixed Points in the Stone-Cech boundary of Groups (ENGLISH)

**Makoto Yamashita**(Univ. Tokyo)Fixed Points in the Stone-Cech boundary of Groups (ENGLISH)

[ Abstract ]

We discuss the class of discrete groups which admit fixed points under the adjoint action on the Stone-Cech boundary. Such groups have vanishing $L^2$-Betti numbers, and nonamenable ones fail to have property (AO).

We discuss the class of discrete groups which admit fixed points under the adjoint action on the Stone-Cech boundary. Such groups have vanishing $L^2$-Betti numbers, and nonamenable ones fail to have property (AO).

### 2010/05/27

16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)

The C*-algebra of codimension one foliations which are almost without holonomy (ENGLISH)

**Catherine Oikonomides**(Univ. Tokyo)The C*-algebra of codimension one foliations which are almost without holonomy (ENGLISH)

### 2010/05/06

16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Connes-Landi Deformation of Spectral Triples (ENGLISH)

**Makoto Yamashita**(Univ. Tokyo)Connes-Landi Deformation of Spectral Triples (ENGLISH)

[ Abstract ]

We describe a way to deform spectral triples with a 2-torus action and a real deformation parameter, motivated by deformation of manifolds after Connes-Landi. Such deformations are shown to have naturally isomorphic K-theoretic invariants independent of the deformation parameter.

We describe a way to deform spectral triples with a 2-torus action and a real deformation parameter, motivated by deformation of manifolds after Connes-Landi. Such deformations are shown to have naturally isomorphic K-theoretic invariants independent of the deformation parameter.

### 2010/04/22

16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)

The Baum-Connes Conjecture and Group Representations (ENGLISH)

**Nigel Higson**(Pennsylvania State Univ.)The Baum-Connes Conjecture and Group Representations (ENGLISH)

[ Abstract ]

The Baum-Connes conjecture asserts a sort of duality between the reduced unitary dual of a group and (a variant of) the classifying space of the group. The conjectured duality occurs at the level of K-theory. For example, for free abelian groups it amounts to a K-theoretic form of Fourier-Mukai duality. The conjecture has well-known applications in topology and geometry, but it also resonates in various ways with Lie groups and representation theory. I'll try to indicate how this comes about, and then focus on a fairly new aspect of the relationship that develops some early ideas of Mackey.

The Baum-Connes conjecture asserts a sort of duality between the reduced unitary dual of a group and (a variant of) the classifying space of the group. The conjectured duality occurs at the level of K-theory. For example, for free abelian groups it amounts to a K-theoretic form of Fourier-Mukai duality. The conjecture has well-known applications in topology and geometry, but it also resonates in various ways with Lie groups and representation theory. I'll try to indicate how this comes about, and then focus on a fairly new aspect of the relationship that develops some early ideas of Mackey.

### 2010/02/18

16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)

Von Neumann Algebras and Boundary Quantum Field Theory

**Roberto Longo**(University of Rome, Tor Vergata)Von Neumann Algebras and Boundary Quantum Field Theory

### 2010/01/21

16:30-18:00 Room #128 (Graduate School of Math. Sci. Bldg.)

On Subfactors Arising from Asymptotic Representations of Symmetric Groups

**山下真**(東大数理)On Subfactors Arising from Asymptotic Representations of Symmetric Groups

### 2010/01/19

16:30-18:00 Room #126 (Graduate School of Math. Sci. Bldg.)

Entire Cyclic Cohomology of Noncommutative Spheres

**高井博司**(首都大学東京)Entire Cyclic Cohomology of Noncommutative Spheres