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 firstname.lastname@example.org.
Post a Comment or Question here...
Thank-you everyone for all your questions and contributions.
... by: Geoff, AustraliaLoad Sudoku: CLICK TO LOAD
I explain all there
... by: RL Purple, UAS, Minnesota
You have given a retired old professor a lot of insights and pleasure on taking up this hobby.
Best of luck
... by: Larry orrick, U S
I've thought of that as well. It would not be appropriate for gentle or moderate puzzles since it would give away too many solved cells, but for diabolical and extremes, it might work. It would mean doubling up the puzzle packs or making them twice the size. That could be done if there was sufficient demand. Otherwise, I could provide a text file with the puzzles to link to the solver, Take Step once would give you the same effect
... by: John Robinson, Western North Carolina
Thank You, JR
... by: Mats Anderbok, SwedenLoad Sudoku: CLICK TO LOAD
Solving singles first and then bi-value cells reduces the number of recursions considerably (but each recursion takes longer time). I will include a counter is the next version of my own solver (Java applet), but I haven't decided yet how to implement it.
The example is a permutation of no. 32632 from Gordon Royle's list (of 47793 puzzles with 17 given) which requires 14,724,893,706 recursions.
... by: PaulyPitts, New Jersey, USA
By the way, your Sudoku site is the very best. It just keeps on getting better and better. Keep up the good work.
Lastly, thanks for the compliment!
... by: pjf, Ontario, CanadaLoad Sudoku: CLICK TO LOAD
Consider 2 pairs; not in a box and not on any on any line.
Those 2 pair define a square.
The other two corners of the square cannot contain any
possibilities of members of the pair.
That's an interesting observation but I don't think it is always true as a general principle. I've picked a random diabolical to look for an example:
D1 and E9 is the pair. E1 contains a 6/8 as well. It forms a short Remote Pair chain and E1 must contain a 6 or 8 as they are the only candidates left. Our pair must contain the same number (either 6 or 8).
So while both opposite corners of the pair cannot contain BOTH numbers they can contain ONE of the numbers - which one though cannot be determined without other strategies.
... by: Arne Hajonides, Wilnis, NetherlandsLoad Sudoku: CLICK TO LOAD
To start with, this is great site.
I have a question about "single's chains, type 1". I'm trying to solve the above puzzle, but I don't understand why the 8 is removed from D9 and not from the another of the cells in the chain (D2, G2, H3, H9)?
With another words, if I start the chain at D9->H9->H3->G2->D2, why is not the 8 removed from D2? (D2 = 8 in the solution and the solution count = 1)
ps. The puzzle is from a Sudoku-book
Which explains it more fully, but your example is a nice clear one. Either the two YELLOW cells will be the solution or the two BROWN cells will be. We don't know which was round. But that means any 8 that can see both colors can't be a solution. It can be removed. Type 1 works off the chain.
... by: Bernard Skehan, USA
Please keep up this site, it is invaluable to beginners and advanced players.
... by: Doug, Hong Kng