SMS scnews item created by Alex Casella at Tue 24 Oct 2017 0909
Type: Seminar
Distribution: World
Expiry: 23 Jan 2018
Calendar1: 30 Oct 2017 1700-1800
CalLoc1: Carslaw 535A
CalTitle1: MaPSS: Mathematical Postgraduate Seminar Series
Auth: casella@ (acas5565) in SMS-WASM

MaPSS: Mathematical Postgraduate Seminar Series: Giulian Wiggins (Sydney University) -- Representation categories and reductive Lie algebras

Dear All, 

We are delighted to present the MaPSS Seminar topic of Monday 30/10; please see the
abstract below.  

**This Semester the Seminar will always run on Monday, at 5:00pm in 535A** 

Following the talk, there will be pizza on offer.  

Speaker: Giulian Wiggins (Sydney University) 

Title: Representation categories and reductive Lie algebras 

Abstract: We introduce some algebraic toys: Algebras with a partition of unity (APoU)
and their representations.  Given such an algebra \(A\), we construct a category, CA, in
which the category of representations of \(A\) is equivalent to the category of linear
functors from CA to the category of vector spaces over the ground field.  As an
application we take a reductive Lie algebra \(g\), and construct an APoU, \(U*g\)
(Lusztigs idempotent form of \(g\)), whose representations are all the integral
representations of \(g\).  Then applying the above theory, we are able to take a \(
(g,A) \)-bimodule \(P\) ( \(A\) is any algebra) satisfying certain conditions, and
derive a presentation for the full subcategory of \(A\) whose objects are direct sums of
the weight spaces of \(P\).  If \(P\) contains a copy of every irreducible \(A\)-module
then the Karoubi completion of this category is the whole category of representations of
\(A\).  As an example, we give a presentation of the category of permutation modules of
\(S_n\) and discuss how a presentation of the category of representations of \(S_n\) may
be obtained from this.  This talk is accessible to anyone with a basic knowledge of
representations of finite dimensional algebras, and of the definitions of category and

Supervisors, please encourage your students to attend.  


MaPSS Organisers

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