## Buildings and Symmetry

The workshop "Buildings and Symmetry", Monday 25th September to Friday 29th September 2017, will be hosted at the School of Mathematics and Statistics of the University of Western Australia, as part of the activities of the Centre for the Mathematics of Symmetry and Computation. The theme of the workshop is relatively broad, including any aspects of buildings and related objects - although as indicated by the title there is an emphasis on symmetries/group theory/Lie theory aspects. Organisers: Alice Devillers (local organiser), Bernhard Mühlherr, James Parkinson, and Hendrik Van Maldeghem

##### News

The Cheryl Praeger Retirement Mini-Symposium was held at the The University of Western Australia (UWA) on the 13th of April 2017. This was to honour the career to date of Cheryl Praeger who began at UWA in 1976 and officially retired at the end of 2016 after 41 years of outstanding service. Cheryl now holds an Emeritus Professorship at UWA. As well as her outstanding research, Cheryl has made enormous contributions to the University, including being Head of School, Deputy Dean of the Faculty, Dean of the School of Graduate Research Studies, Chair of the Promotion and Tenure Committee and member of the University Senate just to name a few. The day consisted of four talks by colleagues Jacqui Ramagge (The University of Sydney), Alice Niemeyer (RWTH Aachen University), Cai Heng Li (Southern University of Science and Technology China) and Martin Liebeck (Imperial College, London). Each speaker included anecdotes about Cheryl that added to the celebratory nature of the day, which concluded with a formal dinner in the evening.

For our 2017 CMSC retreat we again returned to Moondyne Country Convention Centre, in the Avon Valley. As usual the food and atmosphere were excellent, and greatly contributed to our productivity. This retreat was special in that two young members of the CMSC - Alice Devillers' daughter Emilia and Irene Pivotto's son Martin - were able to join us thanks to our CMSC "nanny" Marie Ferland. We also welcomed Gabriel Verret back to Perth to join us for our retreat. This year we recruited Cheryl Praeger to share her expertise in an insightful series of lectures on "Group factorizations and applications to combinatorics". Most of the time was spent working on stimulating problems presented by CMSC members, and our students were kept even more busy with a problem designed for them by Michael Giudici. In the downtime, we took a walk to see the Avon River, swollen by the recent downpours (very unusual for January in Perth), enjoyed an entertaining game of charades and played Michael's "get to know you" puzzle. The latter went swimmingly until Michael decided Yian Xu's childhood pet must have been a panda...

The School of Mathematics and Statistics had a ceremony recognising the fact that Michael Giudici was awarded the Hall Medal and Cheryl Praeger was awarded the Euler Medal by the Institute of Combinatorics and its Applications (ICA). Interim medals were presented by the head of CMSC after a speech by the Head of School.

Saul Freedman has been awarded the 2016 Faculty of Engineering, Computing and Mathematics Medal, for being "the most outstanding honours graduand, having achieved the highest course weighted average in the faculty" in 2016.

Saul Freedman has been selected as one of 200 young researchers worldwide to participate in the 2017 Heidelberg Laureate Forum. The primary purpose of the forum is for these young researchers to meet and learn from laureates of the Abel Prize, the Fields Medal, the Nevanlinna Prize and the ACM A.M. Turing Award.

Shu Jiao Song has taken up a permanent position at Yantai University. We wish Shu Jiao all the very best.

Cheryl Praeger was a judge at the semifinals of FameLab, a science communication competition of the British Council, on 12 April.

Cheryl Praeger gave a colloquium talk at Monash University on 28 April, entitled "Breaking down barriers in Mathematics".

In May Luke Morgan will visit our former colleague Eric Swartz at his new affiliation, The College of William and Mary in Virginia, USA.

Cheryl Praeger will give a colloquium talk at the University of Queensland on 15 May, entitled "Coprime actions of finite groups".

John Bamberg will be giving a presentation at SciTech on 17 May 2017.

In June Luke Morgan will visit another former colleague - Gabriel Verret at the University of Auckland, New Zealand.

Stephen Glasby will visit RWTH Aachen, Germany from 30 June to 18 July.

Stephen Glasby will visit University of Lincoln, UK 1-3 August.

Luke Morgan will attend the Spring Sectional meeting of the American Maths Society and CUNY, New York. He will give a talk in the special session "Infinite Permutation Groups, Totally Disconnected Locally Compact Groups, and Geometric Group Theory".

Michael Giudici will be on sabbatical in the second half of the year. This includes a visit to Tim Burness at University of Bristol in September and October.

Our former visitor, Jin Xin Zhou is in the shortlist for the Mahony Neumann Room Prize, which is for outstanding contributions to the research publications of the Australian Mathematical Society.

##### Visitors

Sabina Pannek (RWTH Aachen), 12-31 May.

Csaba Schneider (Federal University of Minas Gerais), 28 May-11 June.

##### SymOmega

SymOmega is a mathematical blog run by CMSC members John Bamberg, Michael Giudici and Gordon Royle.

##### Conferences

Workshop on Structure in Graphs and Matroids, Waterloo, Canada, 17-21 July 2017. Gordon Royle will attend.

All Kinds of Mathematics Remind me of You: Conference to celebrate the 70th Anniversary of Peter J. Cameron, Lisbon, Portugal, 24-27 July 2017. Michael Giudici and Cheryl Praeger are invited speakers. Stephen Glasby, Luke Morgan, Gordon Royle and Binzhou Xia will attend.

Graph Embeddings and Maps on Surfaces, Podbanské, Slovakia, 30 July-4 August, 2017. Cheryl Praeger is an invited speaker. Michael Giudici, Stephen Glasby, Luke Morgan and Binzhou Xia will attend.

Groups St Andrews 2017, Birmingham, UK, 5-13 August 2017. Michael Giudici, Stephen Glasby, Luke Morgan, Tomasz Popiel, Cheryl Praeger and Binzhou Xia will attend.

Finite Geometries, Irsee, Germany, 10-16 September 2017. John Bamberg is an invited speaker. Tomasz Popiel will attend.

Buildings and Symmetry, Perth, Australia, 25-29 September 2017. John Bamberg is an invited speaker.

Topics on Groups and their Representations in honor of Professor Lino Di Martino on the occasion of his 70th birthday, Palazzo Feltrinelli, Gargnano sul Garda, Italy, 9-11 October, 2017. Michael Giudici will attend.

Combinatorics 2018, Arco, Italy, 3-9 June 2018. John Bamberg is an invited speaker.

##### Papers

### Published papers

J. A. Al-Bar, A. N. Al-kenani, N. M. Muthana and C. E. Praeger, A normal quotient analysis for some families of oriented four-valent graphs, Ars Mathematica Contemporanea 12(2017) 361-381.

C. Amarra, M. Giudici and C. E. Praeger, Affine primitive symmetric graphs of diameter two, Ars Mathematica Contemporanea 13 (2017) 137-165.

J. Bamberg, J. De Beule and F. Ihringer, New non-existence proofs for ovoids of Hermitian polar spaces and hyperbolic quadrics, Annals of Combinatoric 21 (2017) 25-42.

J. Bamberg and M. Lee, A relative m-cover of the Hermitian surface is a relative hemisystem, Journal of Algebraic Combinatorics 45 (2017) 1217-1228.

T. C. Burness and M. Giudici, Permutation groups and derangements of odd prime order, Journal of Combinatorial Theory, Series A 151 (2017) 102-130.

M. Giudici, I. Kovács, C. H. Li and G. Verret, Cubic arc-transitive $k$-multicirculants, Journal of Combinatorial Theory, Series B 125 (2017) 80-94.

D. Mayhew, G. Royle and G. Whittle, Excluding Kuratowski graphs and their duals from binary matroids, Journal of Combinatorial Theory, Series B 125 (2017) 95-113.

C. E. Praeger and S. A. Saxon, Obituary: Wendy Robertson, Gazette of the Australian Mathematical Society 44 (2017) 29-31.

### Accepted papers

A. Alahmadi, S. P. Glasby, C. E. Praeger, P. Solé and B. Yildiz, Twisted Centralizer Codes, to appear in Linear Algebra and its Applications.

J. Al-Bar, A. Al-kenani, N. Muthana and C. E. Praeger, Finite edge-transitive oriented graphs of valency four with cyclic normal quotients, to appear in Journal of Algebraic Combinatorics.

J. Bamberg, J. Lansdown and M. Lee, On m-ovoids of regular near polygons, to appear in Designs, Codes and Cryptography.

N. I. Gillespie and D. R. Hawtin, Alphabet-Almost-Simple 2-Neighbour Transitive Codes, to appear in Ars Mathematica Contemporanea.

M. Giudici, C. H. Li and B. Xia, An infinite family of vertex-primitive 2-arc-transitive digraphs, to appear in Journal of Combinatorial Theory, Series B.

M. Giudici and B. Xia, Vertex-quasiprimitive 2-arc-transitive digraphs, to appear in Ars Mathematica Contemporanea.

L. Morgan, J. Morris and G. Verret, Characterising CCA Sylow cyclic groups whose order is not divisible by four, to appear in Ars Mathematica Contemporanea.

### Submitted papers

J. Bamberg, T. Popiel and C. E. Praeger, Simple groups, product actions, and generalised quadrangles.

J. D. Dixon, C. E. Praeger and A. Seress, Balanced involutions in centralisers of balanced involutions for finite special linear groups of odd characteristic.

M. Giudici, S. P. Glasby, C. H. Li and G. Verret, The number of composition factors of order p in completely reducible groups of characteristic p.

L. Morgan, J. Morris and G. Verret, Digraphs with small automorphism groups that are Cayley on two nonisomorphic groups.

L. Morgan, J. Morris and G. Verret, A finite simple group is CCA if and only if it has no element of order four.

B. Xia, The covering radius of $PGL_2(q)$.