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Feedback and Questions

I've received a lot of interesting comments and questions from Sudoku fans over the last few years and this page is where I try to answer them. Please feel free to drop me a note on the side of the page or try the Facebook comment box. Or you can email me directly at .


Post a Comment or Question here...
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Many thanks to all the people who have helped improve the solvers and strategies with their feedback!

Tuesday 16-Dec-2014

... by: RVtom, USA

Looks like the Jigsaw Shape List pattern numbering is "off by one". The first pattern in the Jigsaw Solver drop down list ("Andrew Stewart 1") matches the second pattern ("Andrew Stuart 2") in the Shape List page, and so on.

Andrew Stuart writes (17-Dec-2014):

Doh! Fixed, thanks!

Monday 8-Dec-2014

... by: RVtom, USA - fulltimer

I enjoy the Jigsaw puzzles the most (so far). Occasionally I like to reenter an older (>30 days old) daily puzzle that is no longer listed. It is tedious to run through the drop down menu to try and find the right "shape". It would be helpful to have either a printed "shape code" associated with each daily puzzle or a separate web page depicting the "shape" associated with each shape name.

Maybe I'm overlooking something you've already provided elsewhere. Thanks for providing this set of web pages!

Andrew Stuart writes (12-Dec-2014):

Good idea, something I've meant to do for a long time. Here it is:

http://www.sudokuwiki.org/Jigsaw_Shape_List

Also links on Jigsaw Solver

All the best

Monday 8-Dec-2014

... by: John, San Bernardino, California

Enjoy playing your 'Daily Sudoku' and 'Jigsaw Sudoku'.
The last few days the 'Jigsaw Sudoku' does not display properly. The Sudoku screen appears, but without numbers or the jigsaw format.

Error message - "can't find sudo".

I updated the Java program but this did not solve the problem.

Help


Andrew Stuart writes (12-Dec-2014):

Yes, I'm working on some new puzzles now. I had my deadline alert set for the end of the month, not so soon!

Saturday 6-Dec-2014

... by: Sharp48, USA

Andrew, I got hooked on Sudoku while I was confined for few weeks few years earlier. My wife presented me with your book " Logic of Sudoku". Fantastic instructions. I understand the entire logic but it is difficult to visualize the patterns that need to be seen. I agree with you that the AIC probably is the Super Theory of Sudoku and I am trying to practice. Thanks for your good work. Best way to preserve Gray matter. Is there a specific forum to help for somewhat of an intermediate level Sudoku player?

Andrew Stuart writes (12-Dec-2014):

Great to hear you are enjoying the game and the site

Longevity is a problem with websites, I'm coming up to ten years, which is unusal. There were several large forums back in the day but they ceased for one reason or another. Of the best that remain, I'd try
http://forum.enjoysudoku.com/

Monday 1-Dec-2014

... by: Mike, Florida

Good system.

Friday 28-Nov-2014

... by: Paul McIlfatrick, Northern Ireland

Andrew

I have your Android App for some time now but the latest version 1.69 engine v2.01a sw360 which became available some days ago crashes each time a new puzzle is entered.

The previous version of the App never crashed on me.

A suggestion for the Android App when entering a new puzzle, please allow the entry of clues and also of solutions as is possible on your Windows PC webpage.

Regards

Paul McIlfatrick

Andrew Stuart writes (28-Nov-2014):

Had a number of reports like that. Going to test again and release a new version asap. Not sure why it does yet but I'll find out

You’d like a distinction between solved and clues on the new puzzle entry? Probably do that

Thanks for the alert!

Monday 27-Oct-2014

... by: Uhm, Netherlands

Load Sudoku:

http://snag.gy/vjBaU.jpg

Here is an picture of Simple Sudoku were i painted the ape your solver did not find.
The blue cells are the pair from ape. combination 6,3 cannot be possible because of the purple colored cell. Combination 6,9 cannot be possible because of the triple colored in orange. So 6 can be excluded from the first blue cell.
This picture is taken right after the first found ape.

About the finned x-wing and grouped x-cycles: finned x-wing stands on place 23 where as you grouped x-cycles stand on place 21, so grouped x-cyles gets executed first so finned x-wings will never get found i think.

Outlook does not want me to send emails, so here again.

Andrew Stuart writes (4-Nov-2014):

I found a rule in my code that says ignore any two cells (your blue cells/my grey cells) which are both bi-value. I have no idea why it was in there, unless I was thinking it was a short cut. But I removed it and found your example. I'm just running some long tests, now, to see what the impact is and if it creates a false positive anywhere.

[edit]
OK the second APE is now showing up in the solver. I detect about 500 more APEs in my test library of 50,000 puzzles (total APE found is around 25,962) so it’s a small but decent increase but there's a 20% increase in time spent looking for APE, but not significant compared to some strats.

Good to be complete (or more complete)



I'll look at the finned x-wings next

[edit]
Uhm can change your reactions

Wednesday 22-Oct-2014

... by: Uhm, Netherlands

Load Sudoku:

You solver does not find the second Aligned Pair Exclusion on J56.
This is in the examle of AIC weak link.

And am i right that there is an overlap between finned x-wing and grouped x-cycles, maybe its better to place the finned x-wing above grouped x-cycles.

Andrew Stuart writes (26-Oct-2014):

Hi Uhm,
Can you provide a screen shot of the second APE? Or a scan? Like to see the full pattern.
There is an overlap, but the solver has very different algorithms for both strategies and I've not investigated the exactness of the overlap. But finned x-wing are above grouped x-cycles in the order, no?
Do leave an email address next time
Cheers

Monday 13-Oct-2014

... by: Francois, Canada

Load Sudoku:

This puzzle has a single solution, but I could not solve it by logic. Started with the only cell that contained 2 candidates, H7 and tried the 3. It produced a puzzle with no solution, so the 9 went in. Had to do this plus trial and error to eliminate candidates as the puzzle kept on getting stuck.
Many days to get to the solution.
Checked most solvers on the internet, and only Brute Force works if at all.
Have you come across this one before, and is there an elegant way to tackle it?

Andrew Stuart writes (14-Oct-2014):

I recognise that puzzle. I posted an article on it:

http://www.sudokuwiki.org/Arto_Inkala_Sudoku

Relatively famous

Monday 6-Oct-2014

... by: Ken Marks, USA Portland Oregon

When I save a partially solved puzzle, it says, saved as a cookie, but when I look in my list of cookies, nothing is there. Could it be that the site is not saving cookies?

Andrew Stuart writes (9-Oct-2014):

It's a mystery where cookies are stored, and different with different browsers.

Do the cookies look like they are doing their job?
There are two on the solver:
1) is automatic and saves the board when you enter a puzzle or 'take step'. That is used to restore the board in case you accidentally close the windows, or just when you come back.
2) there is a manual one - you have to press "save" and "reload" to get that. The board must have changed in order for you to notice a difference when you reload.

Some minor cookies to remember check boxes as well
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