Feedback and Questions

I use your website everyday. It would be nice to have your program on my laptop for use without using the Internet. Do you sell it in that form?

Thanks.

Hello,

Thanks for the great service you are providing us!! I tried your site for the first time a couple of days. Today being frustrated not seeing the XWing in this puzzle I entered the information (twice) and twice got an error after clicking on "next step". I cannot figure out what is creating this other than a bug.

Could you please check it out. Thank you.
Philippe

Just want you to know how much I appreciate the incredible service you provide. Every time I reach a point of frustration, and am sure there is no solution to the puzzle, I go to this site and PRESTO - there it is. I would have stopped attempting the tough puzzles long ago, if not for you. THANK YOU.

I was just using your solver with the sudoku above and it suggested the next move was linked to "X-CYCLE on 5 (Discontinuous Alternating Nice Loop, length 10):
5[D1]-5[D2]=5[G2]-5[G4]=5[F4]-5[E5]=5[E7]-5[J7]=5[J1]-5[D1]-
- Discontinuity is two weak links joined at D1, 5 can be removed from that cell"
I am just learning about X-Cylcle's and wanted to check 2 things: a) do the links have to alternate between weak and strong and b) why isn't F4-E5 a strong link?
Thanks.

Unless I'm missing something, this is a puzzle where the 'diabolical' XYZ Wing strategy can't be applied correctly, but the 'tough' Swordfish strategy can (which is the one your solver applies first). The XYZ strategy seems the easier to identify for me, so I'm used to applying it before Swordfish, but here it doesn't seem to work. I get to the wing represented by E2-F3-H2, which should allow me to remove 4 from D2. That creates 2 more wings for D1-D2-H1 and D1-D2-H2, the latter allowing me to remove 5 from E2. That leaves 5 as the solution for E8, which is wrong. Thus, it appears the Swordfish strategy must take precedence over the XYZ Wing strategy in this case. Am I doing something incorrectly?

Two things: the sudoku I've entered above ("Diabolical" because it uses the "almost locked sets" strategy), and that you can add iCab to your "Tested on:" banner at the top. That is what I use and it works perfectly.

This was a medium level puzzle generated at Road Runner, I believe listing you as the creator. It seems that recent puzzles have more frequently completely blocked solving by applying the three rules (no repeats in row, column, or square). And those weren't identified as particularly hard or fiendish. This forces more complicated strategies, such as the one in this puzzle that when the possibles are listed the nine toward the bottom of the puzzle is the only possible entry for that cell. The Solver goes on to display multiple changes at once and when rows and columns are simultaneously affected, sometimes as many as 6-7 cells solved at one time, it becomes very confusing to try to follow everything going on at once. Suggest perhaps changing the single step (or make it an option) so that only one cell is changed for any given step/cycle. An alternate would be to suggest changing only rows or columns at the same time, but not both, etc.
Thanks,
Dave

Hi Andrew,
why does the Trial-and-Error method not solve this Sudoku sent in by Geoffrey Howell, see Thursday 30-Jul-2009? I tested the Sudoku. A two-step trial is enough to solve it, so rather an easy one, well, relatively speaking.
br, mimi

Solver no longer works beyond simple techniques. No longer free?
Where / how do we sign up and pay?

I have been doing the difficulty 4, 5, 6 Sudoku puzzles since the Vancouver Sun started publishing them in spring 2005, I believe. I NEVER LOOK AT AN ANSWER, since I keep at them until they complete successfully. I also have done the most difficult ones in 2 books. I recently purchased Will Shortz "ferocious sudoku" and have done several of the "Beware, Very Challenging" ones. I enlarge ALL puzzles to about 5.5 inches square on 8.5x11 paper, for easy pencilling. On several, I have got as far as I can go with my own limited logic, and I obviously have another "trick" to learn (which will NOT happen on my own, I am afraid !). I can complete ANY of these by making 2 copies, picking ONE NUMBER of a pair, and seeing if the puzzle completes or dead-ends (then carry on making double copies, as required). Obviously, if the 1st number is wrong, the other MUST be right, etc., etc. I have never read any "rules", but I would like to be able to complete WITHOUT making ANY copies!! MAY I E-MAIL YOU A PUZZLE in which I can go no further, and you can show me ONE additional move (and the logic behind it !). Maybe that is all I need to complete ALL with NO COPIES !? If not, I will be back for another bit of logic ! Will Shortz put me on to this web site ! THANKS