Hi,

Here is the beginning of the final solution to the problem:

All references are 'Row, Column'

Because of the 6 in 4,7 and 5,4 and 7,5; the 6 in the top-right 3x3 square must be in the first column. This means that the only places in the second row that can be either a one or a six are 2,1 and 2,6 (i.e. no longer 2,2 no longer). These are two possible numbers can only go in two cells so no other numbers can go in these two cells. 2,6 was one of only two options for the 7 in the top-middle square. Therefore the 7 goes in 2,4

Afterwards:

7 in 7,6 (only place in column, row and square)

9 in 8,4 (only place in column)

8 in 8,6 (only place in row and square)

8 in 3,4 (only place in row)

5 in 7,4 (only possible number in cell)

2 in 8,5 (only possible number in cell)

And afterwards it is essentially trivial / normal.

BTW, I have written a 'sudoku buddy' programme in Excel that allows you to solve Sudokus on screen. It is complete with notes sections for each cell and there are 7 potential levels of help from none at all to doing all the obvious things for you. You can solve the hardest puzzles on level 6 or 7 by allowing the buddy to do the normal calculations while you focus on the harder strategies (like those needed to solve this puzzle). I usually use level 2 which just points out repeated number errors alone. It is available on

http://www.sudokubuddy.co.uk but the website is not properly sorted yet. I'd love some people to test using it - e-mail me on

andrew@sudokubuddy.co.uk to get a copy (don't worry about the charge on the website - I want some other people to start using it before I'm realistically expecting any money!).

Cheers,

Andrew