I love these puzzles. I'm trying to understand the logic behind them and to do this I've muddled together a work in progress spreadsheet. One of the methods I'm using to look for new logical steps is to put zeros where a number cannot be so that cells where the candidate in question can be placed are more apparent (which has really helped in the past). One of the things I've noticed is that there are a few reccuring patterns of "Available" cells and I was wondering if there was some logic I don't understand or if anyone had any general tips?
One example is from 15th April 2005
Original Numbers
* * 3 | 1 * 6 | 9 * *
* * * | * * * | * * *
* 8 * | 3 5 4 | * 6 *
-----------------------
* 1 * | * 6 * | * 3 *
* 4 * | 7 * 8 | * 2 *
* 5 * | * 2 * | * 9 *
-----------------------
* 6 * | 5 4 3 | * 1 *
* * * | * * * | * * *
* * 1 | 6 * 2 | 4 * *
I got this far...
* * 3 | 1 * 6 | 9 * *
* * * | 2 * * | * * *
* 8 * | 3 5 4 | * 6 *
-----------------------
* 1 * | 9 6 5 | * 3 4
* 4 * | 7 3 8 | * 2 *
3 5 * | 4 2 1 | * 9 *
-----------------------
* 6 * | 5 4 3 | * 1 *
* * * | 8 1 * | * * *
* * 1 | 6 * 2 | 4 * *
Then placing 0's where 3 couldn't be, I got...
0 0 3 | 1 0 6 | 9 0 0
0 0 0 | 2 0 0 | * 0 *
0 8 0 | 3 5 4 | 0 6 0
-----------------------
0 1 0 | 9 6 5 | 0 3 4
0 5 0 | 7 3 8 | 0 2 0
3 5 0 | 4 2 1 | 0 9 0
-----------------------
0 6 0 | 5 4 3 | 0 1 0
0 * 0 | 8 1 0 | * 0 *
0 * 1 | 6 0 2 | 4 0 *
Notice how the cells where 3 can be placed are in the same columns in the left stack and the same rows in the bottom band? Is that significant? I've thought about it for a while and I really can't see a way to place the three using logic or reasoning but I thought I'd ask for another oppinion.
These puzzles are seriously affecting my revision
but once I get to a bit I can't do then I just can't put it down :pAny advice/pointers would be much appreciated,
Thanks,
klkl
