Feedback and Questions

The reason for that convention is because "I" can look like "1", which can be confusing when talking about cell I1 etc, J1 is simply visibly easier. You should not find "I" turning up in any output from the solver or in any of the documentation

Hi, there was an issue on Sunday/Monday in Firefox. Firefox is case-senstive to html element names and I introduced a bug when cleaning up the code. Fixed pretty quickly and printable versions are working in both browsers today. Do have another go

Really glad you wrote in since there was a problem with my diagram. Not sure how but the screen snap shot I took was of a position a few steps before the correct situation. Have a look at the page now. Even I was struggling to make sense of the example because there were stray 4s in D2 and D3. But having removed them it makes sense now.

So, correct, the 4s in D2 and D3 do have to be absent for it to work.

These are recent pages, and I suffer "wood from the trees" syndrome when I check what I write and do.

Appreciated

Thanks for the feedback - appreciated. And good to know its works on Safari as well!

Yep. That is a semi-famous sudoku invented by a Finnish mathematician who claims it is the hardest sudoku ever. Currently aboyt 0.2% of randomly produced sudokus can't be solved with my logical strategy set so there is plenty of work still to do...

Please load your sudoku and click Solution Count. Your sudoku has 5 solutions. When it Takes Step, the solver does not check for multiple solutions. Due to use of strategies that depend on the sudoku having a unique solution, the solver may produce strange results for sudokus having more than one solution. Furthermore, Take Step may find a solution without giving any indication that other solutions exist.

There is an issue with entering numbers and using the back button. Back really only works after you have "taken step" and it is remembering the state the board was in when you pressed that button, not when you entered something. I'd avoid that button for un-doing manually entered numbers

I have started posting a daily sudoku on my site at http://www.scanraid.com/Daily_Sudoku.asp So far, I haven't set up a competition. It does look like the current administrators at sudoku.org.uk have worked out the glitches and are keeping the competitions alive. Since that site is outside my control, I won't speculate on what changes they may implement. However, the problem of experts lists that are top heavy with perfect scores, that I addressed last year, remains. The spread of scores, that we originally had, is long gone. The number of perfect scores continues to grow, resulting in ever more lengthy experts lists. How the new administrators will handle the problem remains to be seen.

I clicked Solution Count and the solver found 14 solutions. The Unique Rectangles strategy is only valid for sudokus that have exactly one solution. Unique Rectangles may remove all solutions from a sudoku that has multiple solutions.

Commonly, multple solutions are the result of omitting one or more givens when entering the puzzle. If you are part way through the solution process when you discover that you left out a given, it is best to Clear and re-enter the whole sudoku. The solver may have already eliminated a candidate that is part of the solution and, thus, no longer be able to find the solution.