### Top Posts

### Recent comments

- Ofir Gorodetsky on A little problem
- Ofir Gorodetsky on A little problem
- gorodetsky on A new constant?
- Ofir Gorodetsky on A little problem
- Peter Cameron on Andrzej Orchel

### Blogroll

- Alexander Konovalov
- Annoying precision
- Astronomy Picture of the Day
- Azimuth
- Bad science
- Bob Walters
- British Combinatorial Committee
- CIRCA tweets digest
- CoDiMa
- Coffee, love, and matrix algebra
- Collecting reality
- Comfortably numbered
- Computational semigroup theory
- DC's Improbable Science
- Diamond Geezer
- Exploring East London
- From hill to sea
- Gödel's lost letter and P=NP
- Gil Kalai
- Haris Aziz
- Intersections
- Jane's London
- Jon Awbrey
- Kourovka Notebook
- LMS blogs page
- Log24
- London Algebra Colloquium
- London Reconnections
- Marie Cameron's blog
- MathBlogging
- Micromath
- Neill Cameron
- neverendingbooks
- Noncommutative geometry
- numericana hall of fame
- Paul Goldberg
- Ratio bound
- Robert A. Wilson's blog
- Sheila's blog
- Since it is not …
- Spitalfields life
- St Albans midweek lunch
- Stubborn mule
- Sylvy's mathsy blog
- SymOmega
- Tangential thoughts
- 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
- Vynmath
- XKCD

### Find me on the web

### Cameron Counts: RSS feeds

### Meta

# Tag Archives: Steiner system

## From M12 to M24

On 20 January 2015, Paul Hjelmstad posted the following question on the GAP forum: Is there an easy way to generate a Steiner system S(5,8,24) for the Mathieu Group M24, if a Steiner system S(5,6,12) for the Mathieu Group M12 … Continue reading

Posted in exposition
Tagged Graham Higman, Jack van Lint, Mathieu group, outer automorphism, Paul Hjelmstad, Steiner system
Leave a comment

## Steiner systems exist

A Steiner system S(t,k,n) is a collection of k-subsets (called “blocks”) of an n-set of “points” with the property that any t-set of points is contained in a unique block. To avoid trivial cases, we assume that t<k<n. Since the … Continue reading

## Symmetry versus regularity

In my report on CAMconf, I didn’t mention Laci Babai’s talk, whose title was the same as that of this post. This was a talk that needed some thinking about. I want to describe the situation briefly, and then pose … Continue reading

Posted in events, exposition, open problems
Tagged primitive group, Seidel switching, Steiner system, strongly regular graph, switching class
4 Comments

## Kirkman’s schoolgirls and their friends

Often it happens that, when I think about a hard problem, I am absolutely convinced that I know what the answer will be, but I merely lack a proof. In this post I want to discuss a problem which I … Continue reading

Posted in exposition, open problems
Tagged affine space, hyperoval, partition, projective plane, Steiner system, Thomas Kirkman
5 Comments