Top Posts
Recent comments
Blogroll
 Astronomy Picture of the Day
 Azimuth
 British Combinatorial Committee
 Comfortably numbered
 Diamond Geezer
 Exploring East London
 From hill to sea
 Gödel's lost letter and P=NP
 Gil Kalai
 Jane's London
 Jon Awbrey
 Kourovka Notebook
 LMS blogs page
 Log24
 London Algebra Colloquium
 London Reconnections
 MathBlogging
 Micromath
 Neill Cameron
 neverendingbooks
 Noncommutative geometry
 numericana hall of fame
 Ratio bound
 Robert A. Wilson's blog
 Since it is not …
 Spitalfields life
 Sylvy's mathsy blog
 SymOmega
 Terry Tao
 The Aperiodical
 The De Morgan Journal
 The ICA
 The London column
 The Lumber Room
 The matroid union
 Theorem of the day
 Tim Gowers
 XKCD
Find me on the web

Join 664 other followers
Cameron Counts: RSS feeds
Meta
Tag Archives: strongly regular graphs
More on the 3p paper
I wrote here about Peter Neumann’s paper on primitive permutation groups of degree 3p, where p is a prime number. Well, summer is almost over, but my undergraduate research intern Marina AnagnostopoulouMerkouri and I have done our work and produced … Continue reading
Peter Neumann’s 3p paper
In 1955, Helmut Wielandt published a paper proving the following theorem: Let G be a primitive permutation group of degree 2p, where p is a prime greater than 3, which is not doubly transitive. Then p = 2a2+2a+1 for some positive integer … Continue reading
Equitable partitions of Latin square graphs
On our recent trip to Shanghai, Rosemary Bailey and I met Sergey Goryainov, who gave a talk about some joint work with his supervisor Alexander Gavrilyuk at the International Workshop on Bannai–Ito Theory in Hangzhou. I mentioned it in my … Continue reading
Posted in Uncategorized
Tagged eigenvalue, equitable partition, Latin squares, quotient matrix, strongly regular graphs
1 Comment
Advanced Combinatorics: the St Andrews lectures
Three years ago, when I joined the School of Mathematics and Statistics at the University of St Andrews, it was suggested that I might like to give a final year MMath module on “Advanced Combinatorics”. No compulsion. Well, of course … Continue reading
Posted in Lecture notes
Tagged Catalan numbers, chromatic polynomial, cycle index, doocot principle, enumeration, formal power series, Friendship Theorem, Gaussian coefficients, generalised line graphs, generalised quadrangles, IBIS groups, line graphs, Mathieu groups, matroid, Moebius inversion, orbitcounting lemma, projective planes, root systems, strongly regular graphs, symmetric Sudoku, triangle property, Tutte polynomial, weight enumerator
Leave a comment
Guessing numbers of graphs
A paper, “Guessing games on trianglefree graphs”, by Anh Dang, Søren Riis, and me, has just appeared in the Electronic Journal of Combinatorics. Here is a brief discussion of what it is about. It is always a pleasant surprise when … Continue reading
London Combinatorics Colloquia
This week saw the two linked London Combinatorics Colloquia, at Queen Mary and the London School of Economics. Not so long ago, a oneday meeting in Reading organised by Anthony Hilton was a fixture of the calendar. When Anthony came … Continue reading