Many of our seminars are Pure Mathematics Colloquia, so why not check here?

## Previous CIRCA & Algebra Semigroups - 2008 to 2009

Previous Pure Mathematics Colloquia from: 2016/17, 2015/16, 2014/15, 2013/14, 2012/13, 2011/12, 2010/11, 2008/09, 2007/08**Wednesday 29th of April, 4pm, Room 1A**

Mickael Gastineau
*(Institut de Mecanique Celeste, Paris)
***An open source library for the Symbolic Computation Software Composibility Protocol
**

We will present an open source C/C++ library (http://www.imcce.fr/Equipes/ASD/trip/scscp/) for the Symbolic Computation Software Composibility Protocol (SCSCP for short, see http://www.symbolic-computation.org/scscp). This framework provides API to develop client applications to access computer algebra systems which support that protocol. Existing computer algebra systems could use this API to provide services to other applications using this protocol. The talk will last about 30 minutes.

**Wednesday 9th of March, 2pm, Room 1A**

Frank Lubeck
*(RWTH Aachen)
***Modifying the definition of Conway polynomials
**

Conway polynomials were defined by Richard Parker to provide standardized models of finite fields. They fulfill a useful compatibility condition with respect to subfields, and they provide generators of the finite field which are primitive roots (they generate the multiplicative group).

Because of this latter condition we can only hope to find such a polynomial for a field with q elements when we know the prime factorisation of q - 1.

I'll explain why it is difficult to compute the Conway polynomials in many cases, although this factorization is known. Furthermore I propose a modification of the definition of Conway polynomials such that these can be easily computed in practice in all cases.

**Wednesday 4th of March, 2pm, Room 1A**

Alexander Konovalov
*(University of St Andrews)
***Parallel computations with the GAP package SCSCP
**

I will present the GAP package SCSCP http://www.cs.st-andrews.ac.uk/~alexk/scscp.htm which allows to organise communication between several local or remote GAP instances, and will show to you how to run parallel computations with this package.

**Thursday 19th of February, 4pm, Room 1A**

Meinolf Sellmann
*(Brown University)
***Context-Free Grammar Constraints
**

When dealing with real-world optimization problems, we frequently face complicated side constraints which are hard to formulate in integer programming and constraint programming. To facilitate the modeling process, we introduce the context-free grammar constraint that requires that an assignment of values to an ordered set of variables must form a word in a given context-free language. For this constraint, we devise an efficient, complete, and incremental filtering algorithm that has the same asymptotic complexity as the Cocke-Younger-Kasami algorithm for parsing context-free languages. Moreover, we show how the constraint can be linearized automatically whereby the resulting polytope has only integer extreme points.

Joint work with Serdar Kadioglu, Louis-Martin Rousseau, Claude-Guy Quimper, and Gilles Pesant

**Wednesday 18th of February, 2pm, Room 1A**

Colva Roney-Dougal
*(University of St Andrews)
***Maximal subgroups of the orthogonal groups**

**Tuesday 2nd of December, 4pm, Room 3B**

Markus Pfeiffer
*(University of St Andrews)
***Automata and growth functions for the triangle groups
**

The triangle groups are a class of finitely presented groups with presentations

t(p,q,r) := <x,y | x^p, y^q, (xy)^r>

for natural numbers p,q,r >= 2. I will present some interesting results on automatic presentations for those groups. I constructed word acceptors for those groups, whose structure mainly depends on the parity of p, q and r.

This enables us to compute growth functions for the triangle groups. For a particular triangle group t(p,q,r) and a generating set A the growth function is of the form

G(x) = P(x)/Q(x)

with P(x) and Q(x) _palindromic_ polynomials with integer coefficients.

**Thursday 20th of November at 4pm in Room 1A**

Nik Ruskuc
*(University of St Andrews)
***Some Combinatorial Properties of Direct Products of Groups, Semigroups and Other Algebraic Structures
**

**Tuesday 4th of November, 4pm, Room 3B**

Colva Roney-Dougal
*(University of St Andrews)
***Permutation groups, orbitals and 2-closure
**

**Tuesday 21st of October, 4pm, Room 3B**

Nik Ruskuc
*(University of St Andrews)
***Diagonal Acts and Applications**