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 andrew@str8ts.com.
Post a Comment or Question here...
... by: reoiutporewiu, home
Load Sudoku: CLICK TO LOAD
While trying some minimum SudokuX puzzles from http://www.sudocue.net/sudokux127193.sdm I found the SudokuX solver fails for 000000000000000000000001000000000100000000000020340000100000053600007000000008020
The puzzle does require (fairly extensive) backtracking to solve but it has only one solution.
The key point at which is fails appears to be in applying the Grouped Xcycles deduction rule. Disabling those rules and going straight to Solution Count fails with the error that it needs at least 17 givens. That's the minimum for normal Sudoku. The minimum for Sudoku X is no more than 12 (the URL above).
Andrew Stuart writes (3Oct2013):
Thanks for this email. I've corrected the message to say 12 clues, but I'm afraid the server will not return a solution count with so few clues. I have to throttle the services since it's a busy machine and the brute force tester sucks CPU. I can confirm my offline solver finds one solution. I have an article about this puzzle. I'd be interested in the first move you found for Grouped Xcycles. Would be nice to make further progress in that area.
... by: bob, california
your fast in getting this program up and running...many thanks cordially, bob nace
Andrew Stuart writes (28Sep2013):
Fixed 'Solve Path' bug. Working as intended again
... by: Brian Maskell, UK
Load Sudoku: CLICK TO LOAD
Possibles show as G7  1/4/5/6/8/9 > 4/5/9 Should be G7  1/4/5/6/8/9 > 4 hence also H8  1/4/7/9 > 9 and F7  2/4/5/6 > 5
Andrew Stuart writes (27Sep2013):
Fixed this also.
... by: DINESH BAGAI, INDIA
Unable to enter the digits on the solver
Andrew Stuart writes (27Sep2013):
Fixed today! Humblest apologies!
... by: gp, usa
looks like the auto clear function needs some work. it's clearing some of the "start " numbers when i enter a solution number.
Andrew Stuart writes (27Sep2013):
Fixed it! Yes, very sorry, I failed to test data entry with autoclear on, because auto clear wasn't checked on my browser, and it wasnt in an area I thought I'd changed. Refresh the solver page.
... by: nevland, TX
the auto clear in the sudoku solver adds errors to the board 26 sept 13
Andrew Stuart writes (27Sep2013):
Fixed today! Humblest apologies! Thanks for the alert
... by: Stefano, Italy
First of all let me say that your application is just amazing, the best I found in the web. Pity I have discovered only now
One bug I found that the agme is not saved at all: when I reload there is no cookie found. Perhaps is my PC. I was using Killer Solver and my OS is Win /. Cookies are allowed Thanks for your answer Regards
Andrew Stuart writes (25Sep2013):
Hi. I use two cookies per solver. One is automatic and remembers your current position on the board  in case you accidentally navigate away or close the window. The second is manual  you have to use the "Save" button and "reload" to get it back. If neither are working then I suspect it is your browser or OS settings, hard to be sure. Definitely working for me though
... by: Michael Gamauf, Austria
When you step through the "Death Blossom" example, it is solved entirely by other strategies.
Andrew Stuart writes (25Sep2013):
I do need to find another example. As the solver slowly changes over time, as I improve it, that will invalidate certain examples of strategies used down the list. It may even make some redundant, even though they are alternative approaches. Thanks for the alert thought, I'll try and find one.
... by: Hamp, the Netherlands (Holland)
I am trying to solve in my newspaper a jigsaw sudoku on a wwekly basis. This jigsaw sudoku has a different pattern every week with patterns that are not listed in your overview. Is it possible to enter this pattern and the numbers that are given? I would appreciate your reply. Thank you and regards. Hamp
Andrew Stuart writes (25Aug2013):
Yes, I'd like to add the ability to enter new shapes. This has never been urgent as I rarely see Jigsaws published even though its my favourite puzzle and a very good puzzle. Does it say who makes them for your newspaper?
... by: Dave H, UK
I am trying to understand Simple Colouring. Looking at your web site I follow it until you start to refer to a 'unit' without explaining what exactly a unit is...
It isn't clear to me from the diagram why some yellowcoloured items are circled red and some are not. Can you explain please ?
Finally, I am not clear as to where to start  you appear to indicate that it isn't important  do I understand that correctly ?
Andrew Stuart writes (25Aug2013):
I'll change the text to introduce a 'unit', that should happen on each article. A Unit is any row, column or box (in normal Sudoku. It might also be a diagonal in Sudoku X and other things in Sudoku variants).
The red circled numbers in the diagram for Rule 2 , highlight those candidates for which a contradiction has been found. In this rule one colour or other will be entirely eliminated (hence marked yellow) but not every yellow candidate is the cause of a contradiction. Might only be two.
Third question  yes. Shouldn’t matter where you start. The new feature on the solver under the list of strategies will help you identify all links. Just have one number shown at a time.
... by: Ray, Iowa, USA
Andrew , love sudoku wiki apps. I use the android and iOS versions. In the android version I can delete old puzzles but I can't see how to do this in iOS version. What am I missing? Thanks, Ray
Andrew Stuart writes (20Aug2013):
I believe a long click on the list of puzzles will delete. I don’t have my iphone to hand to check but I'm pretty sure that’s it
