
Archives
 October 2018
 August 2016
 July 2016
 April 2015
 December 2014
 August 2014
 June 2014
 February 2014
 November 2013
 August 2013
 July 2013
 May 2013
 April 2013
 March 2013
 October 2012
 July 2012
 May 2012
 February 2012
 December 2011
 August 2011
 July 2011
 May 2011
 April 2011
 August 2010
 November 2009
 May 2009
 July 2007
 June 2006
 May 2006

Meta
Category Archives: chatter
Superpermutations: lower bound
I wrote about superpermutations here: a superpermutation is a string that has as substrings all the permutations of some set of symbols. For example, there are six permutations of the symbols 1, 2, 3. They are: 123, 132, 213, 231, … Continue reading
Posted in chatter
4 Comments
Squares of squares, and the group of rational points on the circle
The purpose of this post is to describe a slightly different way of thinking about the existence – or otherwise – of a 3×3 magic square of squares. Of course it may not lead to any real progress, but it … Continue reading
Posted in chatter, Mathematics
1 Comment
Almostmagic squares of squares
In the last post we saw that every 3×3 almostmagic square is a rearrangement of three threeterm arithmetic progressions that have the same common difference. In other words, if we pick any three numbers x, y and z, and any … Continue reading
Posted in chatter, Mathematics
2 Comments
Magic squares of squares: Part I
A recent Numberphile video discussed an intriguing unsolved problem in number theory: is there a 3×3 magic square whose entries are all square numbers? (Matt Parker proposed a solution which doesn’t quite work: see the video for more. The “Parker … Continue reading
Posted in chatter, Mathematics
2 Comments
The Government Statistical Service’s terrible spreadsheet advice
The UK Government Statistical Service recently released its good practice guidance for releasing statistics in spreadsheets. While this advice is clearly wellintentioned*, and parts of it are good, the overall effect is to encourage the release of data in formats … Continue reading
Posted in chatter, Kiln
6 Comments
Tackling the Minimal Superpermutation Problem
What’s the shortest string that contains every possible permutation of ABCD somewhere inside it? As it happens, it’s 33 letters long: ABCDABCADBCABDCABACDBACBDACBADCBA. A string like this is called a minimal superpermutation. So what’s the shortest string that contains every possible … Continue reading
Posted in chatter, Mathematics, news
6 Comments
I hate the Pumping Lemma
I hate the Pumping Lemma for regular languages. It’s a complicated way to express an idea that is fundamentally very simple, and it isn’t even a very good way to prove that a language is not regular. Here it is, … Continue reading
Posted in chatter
44 Comments