CIRCA seminar March 28th

There will be a CIRCA lunchtime seminar on 28th March at 1pm in Theatre D of Maths.

David Stewart (University of Manchester) will speak.

Title: You need 27 tickets to guarantee a win on the UK National Lottery (Jt with David Cushing)

Abstract: The authors came across the problem of finding minimal lottery design numbers j=L(n,k,p,t); that is, a set B_1, …, B_j subsets of {1,..,n} each of size k, such that for any subset D of {1,..,n} of size p, one finds an intersection D\cap B_i with at least t elements. In the context of a lottery, n represents the. number of balls, k the number of choices of balls on a ticket, p the size of a draw.
For the UK national lottery, n=59, k=p=6 and one gets a (rather meagre) prize as long as t is at least 2.
Using the constraint solving library in Prolog, we calculated j for k=p=6, t=2 and n all the way up to 70. For example L(59,6,6,2)=27. This is the second paper where we have aimed to show the value of Prolog and constraint programming in pure mathematics.
I’ll give an overview of constraint programming, logic programming in Prolog, and describe how we used these tools to solve the problem described in the title.

Visit of Arne Van Antwerpen

Arne Van Antwerpen will be here on 16/17/18 May, visiting Olexandr Konovalov.

Arne will give a CIRCA seminar on the Wednesday afternoon, 4-5 in Theatre C.

Title: Multipermutation solutions of the Yang-Baxter equation and nilpotency of skew braces

Abstract: This talk will be based on joint work with Eric Jespers and Leandro Vendramin. The class of multipermutation solutions is a particularly interesting class of solutions of the celebrated Yang-Baxter equation (coming from mathematical physics) with a beautiful combinatorial structure. It was shown that this class corresponds to right nilpotent skew left braces of nilpotent type. In this talk we delve deeper into this class of skew left braces and identify the class of centrally nilpotent skew braces. We discuss that these behave very similar to nilpotent groups and will identify several possible central series for these objects. If time permits, we use this class to illustrate several other key concepts of skew left braces. The talk will be rife with examples and exciting open problems.

All welcome!

Visit of Pascal Schweitzer

Pascal Schweitzer from TU-Darmstadt will visit CIRCA on Wednesday May 10th, and give a talk at 4pm in Maths C. All welcome.

CIRCA lunchtime seminars 2022

The seminars for Autumn 2022 will be held on Thursdays of even weeks at 1pm in Theatre B of Maths. The schedule at present is:

September 22nd: Colva Roney-Dougal and Chris Jefferson

October 6th: Ruth Hoffman and Alan Logan

October 20th: Saul Freedman and Ozgur Akgun

November 3rd: Jendrik Brachter (TU Darmstadt)

November 17th: TBA

December 1st: Michael Young and Peter Cameron

Topics on Groups and their Representations

Colva Roney-Dougal attended the conference “Topics on Groups and their Representations” at the Palazzo Feltrinelli, Gargnano sul Garda, Italy on October 9th – 11th, 2017. She gave an invited talk “Generation of finite groups, with applications to computing normalisers” (see abstract and slides).


Computing with Transformations: Groups and Semigroups

Markus Pfeiffer will speak at the York Semigroup Seminar on 8th November 2017.  The title of his talk is “Computing with Transformations: Groups and Semigroups”, and the abstract can be seen here.

Third Scottish Combinatorics Meeting

The Third Scottish Combinatorics Meeting on 24-25th April was hosted by Sophie Huczynska and Nik Ruskuc. Rosemary Bailey was one of the invited speakers and Matt McDevitt also gave a talk. Other invited speakers included Robert Brignall, who gained his PhD in St Andrews PhD in 2007 and who now works at the Open University, as well as being our Subhonours External Examiner. Following the meeting, Robert stayed from 26-28th April to collaborate with Nik on well quasi ordered-ness of pattern classes of permutations. Another invited speaker, Maura Paterson from Birkbeck, University of London also stayed from 26-28th April to work with Sophie on external difference families and related topics.

Bob Gray’s visit

Bob Gray visited Nik Ruskuc from 10-12th April and gave a talk at the Pure Mathematics Colloquium. Bob was a St Andrews undergraduate and research student at St Andrews, taking his PhD in 2006 and is now a Senior Lecturer at the University of East Anglia in Norwich.

Visitor Madeleine Whybrow: Constructing Majorana Representations in GAP

Madeleine Whybrow, a PhD student from Imperial College London, visited Markus Pfeiffer funded by CoDiMa to work on GAP code supporting her project on Majorana Algebras and the Monster sporadic simple group. She gave a talk on her work at the Pure Mathematics Colloquium. You can find a report on her visit here.