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. I'm also directing Str8ts feedback here. Please feel free to drop me a note on the side of the page. Or you can email me directly at andrew@str8ts.com.
Post a Comment or Question here...
Saturday 12-Nov-2016
... by: Roland, Rüschlikon, Switzerland
Load Sudoku: CLICK TO LOADDaily Sudoku of 9. November 2016, tough:
in this tough Sudoku I tried to find out the clue 49/81 by the xy-chain method. I was not shure if I did it correct. So I watched what the solver does.
It starts a xy-chain at B2 with 2 and 9 in this cell and it ends at G3 with 2 and 9 in this cell too. the solver then markes in A3 and H2 the 2's yellow. Both see the 2's in B2 and G3, once on once off. So the 2's in A3 and H2 are eliminated. Okay, that's what I understand.
But look at the 9 in H2: it can also see both 9's in B2 and G3. So it has to be eliminated too. > We have no more number in cell H2! Impossible.
What is wrong?
I tried to start with this xy-chain at A3 with 1 off / 2 on.
That brought me to impossible eliminations too.
Maybe you can check this and tell me what is the reason?
Thank you very much and best regards,
Roland
You sorta see this with the new "chained" mode for candidates. Select that and then click on 2 in B2. All chains from that 2 will be shown. The 2 in H2 is never part of a chain. The 9 consistently is with most other 9s so that 2 is already suspicious.
Thursday 10-Nov-2016
... by: Anton, Canada
Exocet strategy -- well done! If you remember, we exchanged emails in regards to exocets which started the ball rolling.
If you sent me an email after October 28th, I didn't receive it. As of late October, MuchoMail.com terminated its email service. If you go to MuchoMail.com website, you'll see a notice posted to all its members. (I should have known better. With a funny name like that, something bad was going to happen. Lost all my contacts and emails.)
Is the exocet strategy in beta format? The reason I'm asking is because Puzzle #207 is not an exocet but a double exocet. Your solver doesn't recognize certain kinds of DEs. The solver comes to the point where JC Van Hay has it and your solver says exocet. It's a "collapsed" DE. The first and the second X-Cycles collapses the DE to its bones (1,7,9). Now, if you uncheck Diabolical Strategies and 23 through to 37 -- so you have Basic, Tough Strategies and 22: Exocet checked, and start over, you have an "intact" DE (1,6,7,9). Again, your solver says exocet and not DE. See cenoman's posting which is an "intact" DE. The DE is in its basic form. Same with Puzzle #194. The first and second X-Cycles collapses the DE. Both #207 and #194 are solvable.
As I've stated in my last email, October 4th, about all your DE puzzles: "Many will be solved. All the double exocets for sure”.
Overall, well done Andrew. I'll soon be sending you an email (new address). I'm in transition.
Wednesday 9-Nov-2016
... by: ray, Australia
be made darker?
Ray
Might need to refresh [CRTL]+[F5] to see
Saturday 29-Oct-2016
... by: oscarj, USA
I enjoyed the usage that would let me highlight numbers in the large grid that would show all 1's or all 8's. Now when I click on a number all I get is that number in a small square?
Oscarj
I also wanted it to toggle on/off which the new highlighter allows
Saturday 29-Oct-2016
... by: remmelt, Netherlands
Load Sudoku: CLICK TO LOADThis is a text version of the board useful for posting on forums:
+----------------+----------------+--------------+
| 2469 2469 5 | 379 369 23679 | 236 8 1 |
| 7 1 26 | 4 36 8 | 9 5 236 |
| 3 269 8 | 5 1 269 | 4 7 26 |
+----------------+----------------+--------------+
| 69 8 369 | 1 7 39 | 5 2 4 |
| 149 49 379 | 6 2 5 | 17 39 8 |
| 12 5 27 | 39 8 4 | 17 6 39 |
+----------------+----------------+--------------+
| 269 269 1 | 8 5 369 | 236 4 7 |
| 8 7 4 | 2 369 1 | 36 39 5 |
| 5 3 269 | 79 4 679 | 8 1 269 |
+----------------+----------------+--------------+
Thursday 27-Oct-2016
... by: AV, Canada
I'm using Safari on a Mac. As of today, (Oct. 27/16) I can no longer return to pure edit mode after using the highlighter; the 'possibles' remain coloured. The visual impact is hugely distracting, especially if 1 to 9 have been explored in highlighter mode. How do I revert back to a colour-free edit board?
As for the highlighter itself: once a cell is 'coloured', it stays. By the time I have explored from 1 - 9, all coloured cells are highlighted simultaneously (nothing can be removed).
I have shut the browser, cleared cache and done a reboot. Not happening. I've been so happy with the solver until today ... Please advise.
That edit mode does not clear the highlights is intended. I might add a clear button. You can clear by selecting "chained". I think a clear button might
Thursday 27-Oct-2016
... by: queensvelvet, australia
You should be in edit mode by default now.
The correct cursor should display over the editing box in the cell
The finger is correct for clicking on a number to highlight/chain
Appreciate the alert!
Saturday 15-Oct-2016
... by: STSahasrabudhe, India
Load Sudoku: CLICK TO LOADAre there any 'rules of thumb' for zeroing on a candidate value or two, in r/o which a pattern, a chain or a strategy which will help solve Sudoku, can be looked for?
The reason for my query is that, when stuck in solving a Sudoku printed on paper, I find the job of adding candidates in each unresolved cell rather tedious and feel that there could be a shortcut.i
As to the advanced strategies, well, Sudoku is very deep and most of these were once considered so theoretical that only computers could use them. But they are still the easiest logical step if you don’t want to guess. Most newspaper puzzles do not require them but on my site I am interested in the hard ones. Even now there are some puzzles which cant be solved logically.
Monday 15-Aug-2016
... by: Geomama, UK
I installed the Android app but had to uninstall it because the font is too tiny to see and cannot be adjusted. I did see some other comments to this effect but decided to give it a go anyway based on the photos. Alas, the numbers are nowhere near as big as the photos imply. Please can you make the font size adjustable or just make the numbers fill the boxes. I have low vision and could not even see the numbers but other users are having the same problem! The ability to make the numbers bold and high contrast would be very helpful - or just do this by default to improve everyone's experience!! Thanks for reading.
Sunday 24-Jul-2016
... by: Andrew, England
How are you doing? Thanks for the site.
I'm looking at your solution to a Kenken that I created. The step that I can't understand is as follows:
Killer Innies/Outies
DOG LEG (3): Removing 1/3 from C3
DOG LEG (3): Removing 1/3 from E2
How do you apply the indies/outliers to Kenken with -+/ and x involved? I can only find the reference to Sudoku.
Kind regards
Andrew