Consulting
I am the founder of Hatsya Limited, which provides mathematical and technological solutions to realworld problems.

Recent Posts
Archives
 June 2019
 May 2019
 March 2019
 November 2018
 September 2018
 July 2018
 June 2018
 May 2018
 April 2018
 March 2018
 February 2018
 November 2017
 October 2017
 November 2016
 May 2016
 March 2016
 February 2016
 December 2015
 September 2015
 March 2015
 February 2015
 January 2015
 December 2014
 November 2014
 October 2014
 September 2014
 August 2014
 July 2014
 June 2014
 May 2014
 April 2014
 March 2014
 February 2014
 January 2014
 December 2013
 November 2013
 October 2013
 September 2013
 August 2013
 July 2013
 June 2013
 May 2013
 April 2013
 March 2013
 February 2013
 January 2013
 December 2012
 November 2012
 October 2012
 September 2012
 August 2012
Categories
Meta
Corresponding Facebook page:
Follow me on Twitter
My Tweets
Monthly Archives: August 2013
Four colour theorem
A fascinating paper by Louis Kauffman establishes the equivalence of the fourcolour theorem (the assertion that any planar graph can have its vertices coloured with one of four colours, such that neighbouring vertices have different colours) to the following seemingly unrelated combinatorial … Continue reading
Posted in Uncategorized
5 Comments
Comfortably squarefree numbers
Usually, it is very difficult to find a reasonably naturallydefined sequence which is not present on the Online Encyclopedia of Integer Sequences. The OEIS contains everything from the ubiquitous Bernoulli numbers and the fascinating Golomb selfreferential sequence, to such utterly pointless trivialities as A171056 (the … Continue reading
Posted in Uncategorized
4 Comments
Stella octangula
In this rather popular video, Vi Hart experiments with the patterns that can be formed by connecting the vertices of a regular polygon with straight lines of equal length. In addition to the obvious numbertheoretic interpretation, there is a nice grouptheoretic … Continue reading
Posted in Uncategorized
Leave a comment
Cipher 42: Sudoku II
This can be regarded as a sequel to cipher 21. One of the problems with that cipher was the fact that people could cheat by using an online Sudoku solver; I don’t believe that this suffers from the same vulnerability. … Continue reading
Posted in Ciphers
Leave a comment
A more aperiodic monotile
This article can be regarded as a sequel to my 5 × 5 monotile. Since its announcement, several variants have been discovered. In particular, towards the end of this article we shall present a threedimensional monotile with the following properties: Nonperiodic by … Continue reading
Posted in Uncategorized
Leave a comment
Block cellular automata
On an infinite square lattice, the B36/S125 cellular automaton proceeds similarly to Conway’s Game of Life (B3/S23), but with different birth and survival conditions. Specifically, a dead cell becomes live if surrounded by 3 or 6 live neighbours, and a … Continue reading
Posted in Uncategorized
3 Comments
New aperiodic monotile
In three dimensions, an aperiodic monotile is a solid capable of tiling space, but not in such a way that admits translational symmetry. The question of existence of aperiodic monotiles stems from a weaker question, which formed part of Hilbert’s … Continue reading
Posted in Uncategorized
7 Comments