##### Department of Mathematics,

University of California San Diego

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### Special Combinatorics Seminar

## Koen Thas

#### Gent University, Belgium

## Two lectures on $\mathbb F_1$ -- I. The Weyl functor

##### Abstract:

Starting from the notion of BN-pair (which is closely related to the concept of Tits building), we explain, following a classical insight, how one interprets buildings and their automorphism groups over the nonexisting ``field with one element". (As such, the symmetric groups become Chevalley groups over this ``field".) We then introduce scheme theories in ``characteristic one", and show how these are governed by a deep combinatorial (and motivic) nature.

Host: Jacques Verstraete

### January 15, 2013

### 2:00 PM

### AP&M 7321

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