[Mathsem] New! Mathematics_Colloquium on Thursday, January 23 2014
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k...@imsc.res.in
Jan 21, 2014, 5:29:20 AM1/21/14
to mat...@imsc.res.in, preena...@gmail.com
| Event Notification | Thursday, January 23 2014 | 14:00 - 15:00 |
| Created by: | knr |
| Calendar Name: | Room326 |
| Scheduled for: | Thursday, January 23 2014, 14:00 - 15:00 |
| Category: | Mathematics_Colloquium |
Venue: Room 326
Title: Categorical actions of Coxeter groups and braid groups
By: Ben Elias
From: Massachussets Institute of Technology
Abstract: We all know what it means for a group G to act on a vector space V: one has an endomorphism of V for each element of G, with the obvious compatibility relation. However, one rarely defines a group action in this way! Instead, one simplifies the data required by choosing a presentation of G by generators and relations, and only defining an endomorphism for each generator, checking the relations.
There is also a notion of what it means for a group G to act on a category C. However, given a presentation of a group, it is not at all clear what compatibilities are required to define a categorical action using this presentation. We discuss this problem, which is too difficult to solve in general. Coxeter groups are groups with a particular kind of presentation, generalizing the Weyl groups which appear in representation theory; potential actions of Coxeter groups and braid groups on categories abound in the literature, but are rarely shown to satisfy compatibility. In joint work with Geordie Williamson, we have found the correct compatibility relations for Coxeter groups (and conjecturally for their braid groups). The answer is actually a topological one, dealing with the topology of the Coxeter complex.
Title: Categorical actions of Coxeter groups and braid groups
By: Ben Elias
From: Massachussets Institute of Technology
Abstract: We all know what it means for a group G to act on a vector space V: one has an endomorphism of V for each element of G, with the obvious compatibility relation. However, one rarely defines a group action in this way! Instead, one simplifies the data required by choosing a presentation of G by generators and relations, and only defining an endomorphism for each generator, checking the relations.
There is also a notion of what it means for a group G to act on a category C. However, given a presentation of a group, it is not at all clear what compatibilities are required to define a categorical action using this presentation. We discuss this problem, which is too difficult to solve in general. Coxeter groups are groups with a particular kind of presentation, generalizing the Weyl groups which appear in representation theory; potential actions of Coxeter groups and braid groups on categories abound in the literature, but are rarely shown to satisfy compatibility. In joint work with Geordie Williamson, we have found the correct compatibility relations for Coxeter groups (and conjecturally for their braid groups). The answer is actually a topological one, dealing with the topology of the Coxeter complex.
IMSc Seminar Coordinators
K.N.Raghavan
Jan 22, 2014, 5:51:55 AM1/22/14
to mat...@imsc.res.in, preena...@gmail.com, bel...@math.mit.edu
Note: Change of venue: moved from room 326 to room 123. ---knr
On Tue, Jan 21, 2014 at 03:59:20PM +0530, k...@imsc.res.in wrote:
> Calcium Event Notification
> <br/>By: Ben Elias
> <br/>From: Massachussets Institute of Technology
> <br/>Abstract: We all know what it means for a group G to act on a vector space V: one has an endomorphism of V for each element of G, with the obvious compatibility relation. However, one rarely defines a group action in this way! Instead, one simplifies the data required by choosing a presentation of G by generators and relations, and only defining an endomorphism for each generator, checking the relations.
> <br>
> <br>There is also a notion of what it means for a group G to act on a category C. However, given a presentation of a group, it is not at all clear what compatibilities are required to define a categorical action using this presentation. We discuss this problem, which is too difficult to solve in general. Coxeter groups are groups with a particular kind of presentation, generalizing the Weyl groups which appear in representation theory; potential actions of Coxeter groups and braid groups on categories abound in the literature, but are rarely shown to satisfy compatibility. In joint work with Geordie Williamson, we have found the correct compatibility relations for Coxeter groups (and conjecturally for their braid groups). The answer is actually a topological one, dealing with the topology of the Coxeter complex.
>
>
> IMSc Seminar Coordinators
> _______________________________________________
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On Tue, Jan 21, 2014 at 03:59:20PM +0530, k...@imsc.res.in wrote:
> Calcium Event Notification
> Thursday, January 23 2014
> 14:00 - 15:00
>
> Created by knr
> 14:00 - 15:00
>
>
>
> Calendar Name: Room326
> Scheduled for: Thursday, January 23 2014, 14:00 - 15:00
> Category: Mathematics_Colloquium
>
> Venue: Room 326
> <br/>Title: Categorical actions of Coxeter groups and braid groups
>
> Calendar Name: Room326
> Scheduled for: Thursday, January 23 2014, 14:00 - 15:00
> Category: Mathematics_Colloquium
>
> Venue: Room 326
> <br/>By: Ben Elias
> <br/>From: Massachussets Institute of Technology
> <br/>Abstract: We all know what it means for a group G to act on a vector space V: one has an endomorphism of V for each element of G, with the obvious compatibility relation. However, one rarely defines a group action in this way! Instead, one simplifies the data required by choosing a presentation of G by generators and relations, and only defining an endomorphism for each generator, checking the relations.
> <br>
> <br>There is also a notion of what it means for a group G to act on a category C. However, given a presentation of a group, it is not at all clear what compatibilities are required to define a categorical action using this presentation. We discuss this problem, which is too difficult to solve in general. Coxeter groups are groups with a particular kind of presentation, generalizing the Weyl groups which appear in representation theory; potential actions of Coxeter groups and braid groups on categories abound in the literature, but are rarely shown to satisfy compatibility. In joint work with Geordie Williamson, we have found the correct compatibility relations for Coxeter groups (and conjecturally for their braid groups). The answer is actually a topological one, dealing with the topology of the Coxeter complex.
>
>
> IMSc Seminar Coordinators
> _______________________________________________
> Mathsem mailing list
> Mat...@imsc.res.in
> http://banyan.imsc.res.in/cgi-bin/mailman/listinfo/mathsem
> _______________________________________________
> Mathf mailing list
> Ma...@imsc.res.in
> http://banyan.imsc.res.in/cgi-bin/mailman/listinfo/mathf
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Mat...@imsc.res.in
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