## Madeleine Whybrow’s second visit to St Andrews

I spent a week in St Andrews working with Markus Pfeiffer on an ongoing project which we are working on writing and implementing an algorithm to construct 2-closed Majorana representations. Funding for this trip was provided by CoDiMa.

Majorana algebras are non-associate algebras used to study the Monster group and its subgroups. They can be studied either in their own right, or as Majorana representations of certain groups. Many examples of Majorana algebras have been constructed by hand but it has become clear that, in order to construct bigger and more interesting algebras, a more computational approach is needed.

In a celebrated paper in 2012, Akos Seress announced the existence of an algorithm to constuct 2-closed Majorana representations. Sadly Seress passed away in 2013 and the full details of his algorithm and his results were never published. Recovering his work has been an important aim of the theory ever since.

This was my second visit funded by CoDiMa to work on this project. After the first visit, we had implemented such an algorithm and had started to reproduce Seress’ results. However, constructing Majorana representations is very expensive both in terms of time and memory and so the algorithm requires a lot of optimisation, which was the focus of our work this time around.

The week was a sucess and we have now completely recovered Seress’ results and we are expecting to shortly be able to construct representations larger than those achieved by Seress.

Our work is available on GitHub.

## 8th International Workshop on Parallel Symbolic Computation (PASCO’17)

The 8th International Workshop on Parallel Symbolic Computation (PASCO’17) took place in Kaiserslautern, Germany, July 23-24, 2017, and was co-located with the International Symposium on Symbolic and Algebraic Computation (ISSAC’17). This instance of PASCO continued the mission of promoting and advancing parallel algorithms and software in all areas of mathematical computation. It therefore occupies a unique space in the landscape of international conferences and workshops, that brings together (parallel) systems developers and theoreticians in the broad area of mathematical software, in particular for symbolic computation. As in previous instances, PASCO’17 was generously supported by Maplesoft, who donated 2 Maple licences for the recipients of the best paper and the best student paper awards in the programme of PASCO’17. Details about the event can be found in the preface to the PASCO’17 proceedings, published in the ACM Digital Library: https://dl.acm.org/citation.cfm?id=3115936&picked=prox

The travel funding by Codima allowed me (Hans-Wolfgang Loidl) to attend this event, as General Chair for PASCO’17, in person and to oversee the running of the workshop. I was particularly pleased by the good attendance for the sessions of this event: the workshop programme contained a total of 13 contributed papers, reflecting the focused nature of this workshop, but attendance to the sessions was in the range of 30-40 academics and students, as well as representatives from Maplesoft and other companies. This reflects the wider interest in the high-performance aspects of this field.

From a Codima point of view, this was a good opportunity to flag the presence of this UK network and to strengthen its international connections. Codima members have been involved in the running of this event as General and Publicity chairs, and continue to take a leading role in the growing of this community. New links have been established between Codima members and the invited speakers from PASCO’17: the group in Glasgow is in collaboration with Prof Florent Hivert, on parallel symbolic algorithms in the area of semigroup enumeration. We hope to further firm up these links by inviting Prof Hivert for a research visit to Scotland.

Hans-Wolfgang Loidl (Heriot-Watt)

## Carnival of Mathematics #150

Welcome to the **150th Carnival of Mathematics**. This is a monthly digest of selected mathematical blogs, hosted each month on a different site. The 1st Carnival has been published in February 2007, so this tradition already continues for more than 10 years. Thanks to everyone who submitted their blog posts to the 150th Carnival!

Following the tradition, we first ask what do we know about 150. It is the number of groups of order 900, the number of integer solutions to x^{2}+y^{2}+z^{2} = 15^{2} (allowing zeros and distinguishing signs and order), and the number of squares on the 5x5x5 Rubik’s cube. It is a Niven number (aka Harshad number), i.e. it is divisible by the sum of its digits, and an abundant number, i.e. the sum of its divisors exceeds 2×150.

Now to the highlights of some recent mathematical blogs. Ben Orlin, the author of Math with Bad Drawings blog, published new post (with drawings!) called The State of Being Stuck. It is based on Andrew Wiles’ answer to the question by Ben asked at the Heidelberg Laureate Forum 2016. Being stuck is a part of the research process, and is not something to be afraid of – this is what Andrew Wiles would like to emphasize when talking about mathematics to a broader public. This year, Ben went to the Heidelberg Laureate Forum again, and you may find his account of the event here. Another blog post about the Heidelberg Laureate Forum 2017 has been published by Katie Steckles on the Aperiodical.

And if you’re stuck at something and need a break, then perhaps you may find inspiration through looking at nature’s beauty – for example, LThMath suggests to look at Symmetry and Butterflies, which may reflect concepts from various areas of mathematics, ranging from analysis to algebra and statistics.

Speaking of statistics, John D. Cook discusses an interesting application in Randomized response, privacy, and Bayes theorem. Suppose you have a database with sensitive information, and you would like deliberately corrupt it with random noise to anonymise records. How this can be done in a way to preserve privacy while still keeping the data statistically useful?

Rachel Traylor wrote several posts for The Math Citadel website: The Central Limit Theorem Isn’t A Statistical Silver Bullet, where she shows how The Central Limit Theorem, for all its power and popularity, is not a one-stop result to be used for all occasions, and Cauchy Sequences: The Importance Of Getting Close. The latter is a wonderfully accessible explanation of the Cauchy property of sequences, taking time to rigorously examine every piece of the definition.

Anthony Bonato has been interviewing prominent mathematicians in a series of blog posts, most recently Eugenia Cheng, researcher in category theory and the author of *How to Bake Pi* and *Beyond Infinity*, and Jennifer Chayes, one of the leading researchers in network science, working at the interface of mathematics, physics, computational science and biology.

Now to discrete mathematics. Reduce The Problem: Permutations And Modulo Arithmetic is another post by Rachel Traylor which in a very accessible manner explains permutation and introduces the concept of isomorphism.

In EKR, Steiner systems, association schemes, and all that, Peter Cameron discussed a class of graphs which give a context to two major results in combinatorial mathematics: the construction of Steiner systems, and the Erdős–Ko–Rado theorem (this story has a continuation in his later post here). Steiner systems also lead to a winning strategy in the card game described in the post MINIMOGs and Mathematical blackjack by David Joyner.

In the Quanta Magazine, Erica Klarreich writes about the recent result on O’Nan moonshine by Ken Ono, John Duncan and Michael Mertens (see their paper Pariah moonshine in Nature Communications) in her article Moonshine Link Discovered for Pariah Symmetries. Another new article in the Quanta Magazine is Mathematicians Measure Infinities and Find They’re Equal by Kevin Hartnett. It introduces recent results by Maryanthe Malliaris and Saharon Shelah, which lead to their Third Hausdorff Medal 2017 award.

Ian Gent published Why the world’s toughest maths problems are much harder than a chess puzzle, and well worth US$1m at The Conversation. There he explains the *n*-queens completion problem and gives some comments to the recent paper written by Chris Jefferson, Peter Nightingale and Ian Gent and published in the Journal of Artificial Intelligence Research, where they show that this problem is NP-complete.

Several posts in September reported news on mathematical software and its applications, in particular Parallel multivariate multiplication by Bill Hart, and Types of Gaussian Elimination and more technical High Performance Meataxe Interface redesign by Richard Parker. Katie Steckles reported about the new largest generalised Fermat prime, discovered by the PrimeGrid project.

**Next Carnival**

151th Carnival of Mathematics will be hosted by Frederick at White Group Mathematics. Please see the main Carnival website for further details and the form to submit blog posts to the new Carnival.

## We are hosting Carnival of Mathematics 150

The **Carnival of Mathematics** is a monthly digest of mathematical blogs, hosted by a different blog each month. The 150th Carnival of Mathematics will be published here at the CoDiMa website. Submissions are accepted until the end of September. To see further guidelines and submit at item to Carnival 150, please see this page. You may also find there links to all previous carnivals.

## GAP 4.8.8 release

GAP 4.8.8 release, which also includes 30 package updates, has been announced today and is now available for download from the GAP website. Please also see the release announcement in the GAP Forum.

## Leonard Soicher’s visit to Portugal

The CoDiMa project supported my participation in “All Kinds of Mathematics Remind me of You: Conference to celebrate the 70th Anniversary of Peter J. Cameron“, held at the University of Lisbon, 24-27 July 2017. This conference brought together many colleagues, students and collaborators of Peter Cameron, and a diverse range of interesting mathematical research (covering Peter’s diverse range of interests) was presented and discussed.

This conference gave me the opportunity to present and discuss my recent algorithms and programs (in GAP/GRAPE) to exploit graph symmetry in graph colouring, in particular in the difficult problem of computing the chromatic number of a graph. I was also able to discuss the application of these programs to the determination of the “non-synchronizing” primitive permutation groups (of interest to researchers in semigroup and automata theory) of degree at most 255.

## Groups, Rings and the Yang-Baxter equation

In June 2017 Alexander Konovalov took part in the conference “Groups, Rings and the Yang-Baxter equation” (Spa, Belgium). He gave a talk “GAP Group Rings Toolkit” with an overview of the functionality to work with group rings available in GAP and four of its packages, demonstrated the Jupyter kernel for GAP, and organised a coding sprint to work on the Wedderga package. As a result, Wedderga development version has been migrated from Bitbucket to GitHub (https://github.com/gap-packages/wedderga), and a new collaborator, Dr Sugandha Maheshwary (ISER Mohali), had submitted her first pull request to Wedderga.

## GAP training events in Summer 2017

We will run two additional GAP tutorials in the UK this summer:

- GAP tutorial as a part of the
**Summer School on Finite Geometry**in Brighton on 26th-30th June 2017. - GAP tutorial on August 13th-14th as a satellite event to the
**Groups St Andrews 2017 in Birmingham**. It has independent registration from Groups St Andrews. The deadline for booking discounted accommodation on campus is**July 25th**, after that it will be only available at standard price subject to availability. See**this page**for further details and the link to the registration page.

## Visitor Madeleine Whybrow: Constructing Majorana Representations in GAP

After meeting at the Workshop on Permutation Groups: Methods and Applications in Bielefeld in Germany, Markus Pfeiffer became interested in some computational work which I am developing as part of my PhD. He kindly invited me to St Andrews to spend a week working together on my code. Funding for this trip was provided by CoDiMa.

The work concerns developing and implementing an algorithm which can construct Majorana algebras, objects which occur in the study of the Monster group and its associated representation, the Griess algebra. In particular, I am interested in studying these algebras as Majorana representations of certain finite groups.

The algorithm takes as its input a finite group and a generating set of involutions. It considers all possible Majorana representations of the group with respect to the generating set and then, for each representation, either attempts to construct it or shows that it cannot exist.

In 2012, Akos Seress announced that he had constructed such an algorithm and published a list of groups whose Majorana representations he had been able to classify. However, Seress sadly passed away before he was able to publish the details of either his algorithm or of the representations which he had constructed. Reproducing his work has been an important aim of Majorana theory ever since.

The code is currently able to construct the Majorana representations of some groups, but we have not been able to reproduce the full results of Seress’ work. Together, we have been working on improving the methods in the algorithm to extend its capabilities. Improvements can come either from better implementation of the current methods, or from finding new approaches from theoretical work on the algebras.

This work is of particular interest as these algebras are defined over the reals and their construction involves some linear algebra over rational numbers. Improving GAP’s functionality over fields of characteristic zero is something which is being actively worked on and will benefit this problem as well as many others.

I also got the opportunity to present my work at the School of Mathematics and Statistics’ Pure Colloquium.

Overall, the week was very productive and we look forward to working together in the future.

## Computational Mathematics with Jupyter

Jointly with the Horizon 2020 **OpenDreamKit** project, we have organised the workshop **“Computational Mathematics with Jupyter”**, which took place at the** International Centre for Mathematical Sciences** in Edinburgh on 16-20 January 2017. You can find some reports from the workshop here:

**Computational Mathematics with Jupyter**by Raniere Silva (Software Sustainability Institute) and Hans Fangohr (University of Southampton)**Computational Mathematics with Jupyter: Sprint**by Raniere Silva (Software Sustainability Institute)- Storify of
**#JupyterICMS**tweets