## Operator Algebra Seminars

Seminar information archive ～04/19｜Next seminar｜Future seminars 04/20～

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

### 2012/05/02

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

A measurable group theoretic solution to von Neumann's Problem (after Gaboriau and Lyons) (JAPANESE)

**Yuhei Suzuki**(Univ. Tokyo)A measurable group theoretic solution to von Neumann's Problem (after Gaboriau and Lyons) (JAPANESE)

### 2012/04/25

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

Bost-Connes system and class field theory (JAPANESE)

**Takuya Takeishi**(Univ. Tokyo)Bost-Connes system and class field theory (JAPANESE)

### 2012/04/18

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

Classification of Group Actions on Factors (after Masuda) (JAPANESE)

**Koichi Shimada**(Univ. Tokyo)Classification of Group Actions on Factors (after Masuda) (JAPANESE)

### 2012/04/11

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

Mathematical Aspects of Fractional Quantum Hall Effect (ENGLISH)

**Shweta Sharma**(Univ. Paris Sud)Mathematical Aspects of Fractional Quantum Hall Effect (ENGLISH)

### 2012/03/23

16:30-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)

Higher Rank Graph $C^*$-algebras (ENGLISH)

**Alex Kumjian**(University of Nevada, Reno)Higher Rank Graph $C^*$-algebras (ENGLISH)

### 2012/02/02

16:30-18:00 Room #002 (Graduate School of Math. Sci. Bldg.)

Weak Exactness for $C^*$-algebras and Application to Condition (AO) (JAPANESE)

**Yusuke Isono**(Univ. Tokyo)Weak Exactness for $C^*$-algebras and Application to Condition (AO) (JAPANESE)

### 2012/01/26

16:30-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)

The transverse fundamental class of linear foliations

on torus bundles over the circle (ENGLISH)

**Catherine Oikonomides**(Univ. Tokyo)The transverse fundamental class of linear foliations

on torus bundles over the circle (ENGLISH)

### 2012/01/16

16:30-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)

Is an irng singly generated as an ideal? (JAPANESE)

**Narutaka Ozawa**(RIMS, Kyoto University)Is an irng singly generated as an ideal? (JAPANESE)

### 2012/01/06

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

Diagrammatical methods in theory of subfactors (ENGLISH)

**Yasuyuki Kawahigashi**(Univ. Tokyo)Diagrammatical methods in theory of subfactors (ENGLISH)

### 2012/01/05

16:30-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)

Classification and amenability in theory of von Neumann algebras (ENGLISH)

**Yasuyuki Kawahigashi**(Univ. Tokyo)Classification and amenability in theory of von Neumann algebras (ENGLISH)

### 2011/12/27

14:30-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)

Deformation of algebras associated to group cocycles (JAPANESE)

Construction of wedge-local nets through

Longo-Witten endomorphisms (JAPANESE)

**Makoto Yamashita**(Universita di Roma "Tor Vergata") 14:30-16:00Deformation of algebras associated to group cocycles (JAPANESE)

**Yoh Tanimoto**(Universitaet Goettingen) 16:30-18:00Construction of wedge-local nets through

Longo-Witten endomorphisms (JAPANESE)

### 2011/11/22

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

Stability of topological phases of matter (ENGLISH)

**( Institute for Quantum Information and Matter (Caltech))**

Spyridon MichalakisSpyridon Michalakis

Stability of topological phases of matter (ENGLISH)

[ Abstract ]

The first lecture will be an introduction to quantum mechanics and a proof of Lieb-Robinson bounds for constant range interaction Hamiltonians. The second lecture will build on the first to prove a powerful lemma on the transformation of the interactions of generic gapped Hamiltonians to a new set of rapidly-decaying interactions that commute with the groundstate subspace. I call this "The Energy Filtering Lemma". Then, the third lecture will be on the construction of the Spectral Flow unitary (Quasi-adiabatic evolution) and its properties; in particular, the perfect simulation of the evolution of the groundstate subspace within a gapped path. I will end with a presentation of the recent result on the stability of the spectral gap for frustration-free Hamiltonians, highlighting how the previous three lectures fit into the proof.

The first lecture will be an introduction to quantum mechanics and a proof of Lieb-Robinson bounds for constant range interaction Hamiltonians. The second lecture will build on the first to prove a powerful lemma on the transformation of the interactions of generic gapped Hamiltonians to a new set of rapidly-decaying interactions that commute with the groundstate subspace. I call this "The Energy Filtering Lemma". Then, the third lecture will be on the construction of the Spectral Flow unitary (Quasi-adiabatic evolution) and its properties; in particular, the perfect simulation of the evolution of the groundstate subspace within a gapped path. I will end with a presentation of the recent result on the stability of the spectral gap for frustration-free Hamiltonians, highlighting how the previous three lectures fit into the proof.

### 2011/11/17

16:30-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)

Hecke pairs in ergodic measured equivalence relations (JAPANESE)

**Takehiko Yamanouchi**(Tokyo Gakugei University)Hecke pairs in ergodic measured equivalence relations (JAPANESE)

### 2011/10/07

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

Towards the classification of non-simple $C^*$-algebras of real rank zero (ENGLISH)

**Takeshi Katsura**(Keio University)Towards the classification of non-simple $C^*$-algebras of real rank zero (ENGLISH)

### 2011/07/21

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

Almost completely isometric maps and applications (ENGLISH)

**Jean Roydor**(Univ. Tokyo)Almost completely isometric maps and applications (ENGLISH)

### 2011/07/14

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

New perspectives for the local index formula in noncommutative geometry (ENGLISH)

**Raphael Ponge**(IPMU)New perspectives for the local index formula in noncommutative geometry (ENGLISH)

### 2011/06/16

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

Introduction to rigidity theory of von Neumann algebras (JAPANESE)

**Yusuke Isono**(Univ. Tokyo)Introduction to rigidity theory of von Neumann algebras (JAPANESE)

### 2011/06/09

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

On the free Fisher information distance and the free logarithmic Sobolev inequality (JAPANESE)

**Hiroaki Yoshida**(Ochanomizu Univ.)On the free Fisher information distance and the free logarithmic Sobolev inequality (JAPANESE)

### 2011/04/14

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

Amenable actions and crossed products of $C^*$-algebras (JAPANESE)

**Masayoshi Matsumura**(Univ. Tokyo)Amenable actions and crossed products of $C^*$-algebras (JAPANESE)

### 2011/02/18

10:30-12:00 Room #122 (Graduate School of Math. Sci. Bldg.)

Dirac families and 1-cocycles (ENGLISH)

**Pedram Hekmati**(Univ. Adelaide)Dirac families and 1-cocycles (ENGLISH)

[ Abstract ]

Families of Dirac type operators, transforming covariantly under the projective action of the loop group $LG$, determine a class in twisted K-theory on compact Lie groups $G$. The loop group is the gauge group of a principal $G$-bundle over the circle and an interesting problem is to try to generalise the circle to a higher dimensional compact manifold. This is far from obvious and some of the difficulties can be modelled in a slightly simpler setting, by replacing $LG$ and gauge connections by objects which have only small differentiability in the Sobolev sense. In this talk, I will provide some background to this problem and explain how 1-cocycles naturally appear in this construction.

Families of Dirac type operators, transforming covariantly under the projective action of the loop group $LG$, determine a class in twisted K-theory on compact Lie groups $G$. The loop group is the gauge group of a principal $G$-bundle over the circle and an interesting problem is to try to generalise the circle to a higher dimensional compact manifold. This is far from obvious and some of the difficulties can be modelled in a slightly simpler setting, by replacing $LG$ and gauge connections by objects which have only small differentiability in the Sobolev sense. In this talk, I will provide some background to this problem and explain how 1-cocycles naturally appear in this construction.

### 2011/02/10

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

Symplectic and quantum categories (ENGLISH)

**Alan Weinstein**(UC Berkeley)Symplectic and quantum categories (ENGLISH)

### 2011/01/28

14:45-16:15 Room #122 (Graduate School of Math. Sci. Bldg.)

Semiprojectivity of graph algebras (ENGLISH)

**Takeshi Katsura**(Keio University)Semiprojectivity of graph algebras (ENGLISH)

### 2011/01/27

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

Entire Cyclic Cohomology of Noncommutative Riemann Surfaces (JAPANESE)

**Hiroshi Takai**(Tokyo Metropolitan University)Entire Cyclic Cohomology of Noncommutative Riemann Surfaces (JAPANESE)

### 2011/01/20

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

Property (TT)/T and homomorphism rigidity into Out$(F_n)$ (JAPANESE)

**Masato Mimura**(Univ. Tokyo)Property (TT)/T and homomorphism rigidity into Out$(F_n)$ (JAPANESE)

### 2011/01/18

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

Scattering induced current in a tight binding band (ENGLISH)

**Claude-Alain Pillet**(Univ. de Toulon et du Var)Scattering induced current in a tight binding band (ENGLISH)