
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
Author Archives: Robin Houston
Revisiting “On editing text”
This document is an incomplete draft. About two years ago I wrote about a categorytheoretic treatment of collaborative text editing. That post is unique in the history of Bosker Blog in having been cited – twice so far that I know … Continue reading
Posted in algorithms, category theory, Mathematics
2 Comments
Decoding the mysterious symmetry of the bicycle lock numbers
Suppose you have a lock of this sort that has n dials and k numbers on each dial. Let m(n, k) be the minimum number of turns that always suffice to open the lock from any starting position, where a turn … Continue reading
Posted in Mathematics
Leave a comment
The bicycle lock problem
Don’t lock your bicycle with a combination lock. Someone will steal it: I learnt this the hard way. It’s quite easy to open a combination lock by feel, without knowing the combination. Try it: with a bit of practice, you … Continue reading
Posted in algorithms, Mathematics
4 Comments
Beyond Bézier curves
There is a new feature of Pages and Keynote, not mentioned in any of Apple’s publicity nor in any press coverage I’ve seen, that is really very interesting. Perhaps it will even one day prove to have been revolutionary, in … Continue reading
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
The algebra of Unix command substitution
Shadab Ahmed raised an interesting question. Open a Unix command shell, type : ‘!!’ and press return. Then type : “!!” ‘!!’ and press return. Now repeat the following a few times: press the up arrow, and press return.
Posted in Mathematics
6 Comments
“Venn diagram” partitioning
Paddy3118 wrote about partitioning elements in the same way a Venn diagram does. So, if we have sets A, B and C, the partitions are
Posted in algorithms, chatter
Leave a comment