Fifty-sixth BLOC meeting


Bristol Leicester Oxford Colloquium

The 56th BLOC meeting will be held on Monday 16th April 2012 at The University of Kent and immediately precedes the BMC.

It is hoped that all participants will attend both the BLOC meeting and the BMC. Please note that participants at the BMC MUST register for the BMC.



12:00-12:45 Alison Parker (Leeds) Hochschild cohomology and a question of Happel

12:50-13:35 Abbie Halls (Aberdeen) Involutions and Kazhdan-Lusztig cells in Coxeter groups


14:40-15:25 Raquel Simoes (Leeds) Hom-configurations and noncrossing partitions

15:45 Opening of the BMC


All talks will take place in the Maths Lecture Theatre, Mathematics Institute, University of Kent.


Alison Parker: Hochschild cohomology and a question of Happel
We begin with an introduction to Hochschild cohomology, an important invariant in the representation theory of algebras, and an overview of some of the properties of the Hochschild cohomology ring for self-injective algebras. The main part of the talk focuses on the particularly rich class of self-injective algebras which arise in the representation theory of U_q(sl_2), and we will give an overview of the structure of the Hochschild cohomology ring for these algebras. As a consequence we give a wide class of algebras which answer negatively a question of Happel, in that they have finite Hochschild cohomology ring but infinite global dimension. This further extends a result of Buchweitz, Green, Madsen and Solberg, and Snashall and Taillefer. This talk is based on joint work with Snashall.

Abbie Halls: Involutions and Kazhdan-Lusztig cells in Coxeter groups

Let H be the single parameter Hecke algebra associated to a finite Coxeter group W. Lusztig and Vogan recently defined an action of H on the free module generated by the involutions of W. This module admits a distinguished basis with polynomial coefficients which is closely related to the Kazhdan Lusztig basis of H. I will discuss the properties of this basis, its relationship to the Kazhdan Lusztig cells of W and an efficient algorithm which partitions the involutions of W into cells.

Raquel Simoes: Hom-configurations and noncrossing partitions

Let Q be a Dynkin quiver and D^b(Q) the bounded derived category of the path algebra associated to Q. We will give a bijection between maximal Hom-free sets of indecomposable objects (the Hom-configurations in the title) in a certain orbit category of D^b(Q) and noncrossing partitions in the Weyl group associated to Q which are not contained in any proper standard parabolic subgroup. This bijection generalizes a result of C. Riedtmann arising in her work classifying the representation-finite selfinjective algebras of tree class A_n.

The BMC webpage with details of the programme and registration/ accommodation costs is here. Note that the reduced registration fee for the BMC ceases on 16th March.

Please let Rowena Paget or Nicole Snashall know by April 10th if you are coming to the BLOC meeting.  

BLOC is supported by an LMS Scheme 3 grant, which is used to help offset travel costs for participants, with priority given to covering travel and accommodation costs for speakers and postgraduates. Funds are very limited so if participants can find funding from other sources that is helpful! For more information about funding for this meeting, please email Nicole Snashall.

Travel information is HERE

There will be time for informal discussions during the meeting. 

For further information please contact one of the organisers:

Joe Chuang
Karin Erdmann
Jeremy Rickard
Nicole Snashall


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