Logic Masters Deutschland e.V.

on 26. September 2024, 19:29 by Zaaphod
Hi sujoyku,
Thank you for the help. I see what you are getting at. It does make sense, and I've done what you describe for other puzzles, but for them I only needed to look ahead 2 or 3 moves to prove which way it needed to be. with this one, no matter what I picked, I needed to look ahead a minimum of 7 moves to find a contradiction.
While I found this quite challenging, I really did enjoy it.
I find it quite amazing that TidePool was able to come up with the way this interlocks together.

on 23. September 2024, 22:48 by sujoyku
Hey Zaaphod,
BUG is not a form of guessing but it sort of uses uniqueness, i.e. assumes the puzzle only has one valid solution. If there was the pattern that I described this would contradict uniqueness. Another way which I usually went before I learned about the BUG was the following: Pick one candidate X that can only appear in two cells in the given row or column and which is part of the options in your tri-value cell. Then you can check which digit goes there if X is in the other position. The third candidate then can be eliminated and you will be able to place a digit which resolves the rest of the puzzle.

on 23. September 2024, 22:04 by Zaaphod
Hi sujoyku,
Am I missing something?

Is there some fancy technique to resolve this other than to pick any one of the pairs, pick a way for it to be, try to solve it the rest of the way and either solve it, or hit a conflict, go back and change it to the opposite way, then solve it?

I thought all these puzzles were meant to be solved with zero guessing and picking one way for a cell to be without having a logical reason for choosing that digit feels like I am missing some logical path to the solution as it was meant to be discovered.

Or is it common to just recognize the BUG (thanks for telling me it has a name) and just stop looking for a logical reason for each digit and pick one state and just see how far you get? To me this is just guessing.

I am really curious if there is some other way to solve this other than to just pick a state for one of the pairs and try it.

For me it's not about getting the correct digits in the correct cells, it's about seeing the logic that leads to it. I could solve any sudoku by just sticking random numbers in every cell and hitting the checker after each one to see if that's good or not, but that completely defeats the entire point of doing the puzzle, you would miss the elegance of solving it purely logically with no guessing.

on 23. September 2024, 16:32 by sujoyku
Hey Zaaphod, I think why me and others have given 1 star difficulty is because you get along rather easily until you reach the point you mentioned. At that stage, so much of the grid is filled in that it is also not too hard to deduce the last bit by look-ahead methods. The BUG (bi-value universal grave) is a method that is widely known, but maybe not entirely standard. From a theoretical stand-point, it forbids a valid puzzle having two candidates in each remaining cell. In that case, you could flip all choices and arrive at two possible solutions. As a consequence, that yields a restriction for the three-values cell to avoid such a pattern.

on 23. September 2024, 16:26 by Zaaphod
No way is this one star. I find it quite challenging. I would consider myself a beginner, and I can solve all the one star puzzles on here, including a few where I had to do some coloring to figure it out, but I can't figure out how to do this one. I've got it to the point where the entire grid is either filled in, or there is a choice of 2 digits in every other box, except one that has 3 possibilities, and I just can't see how to resolve it. The non-standard technique is not something a one-star puzzle solver like me will see easily... I've been looking at this for 3 hours and I can't see how to resolve it...
I have pairs of digits in 3 rows and no way to unwind them. I could solve it by just picking one of the pairs and guessing one way and see if it works, but I'm sure that is not necessary, and I would rather keep staring at it and try to find the logic that will resolve all these pairs.
That one non-standard technique is DEFINATLY enough to put this out of the one star category.

on 20. August 2024, 00:07 by sujoyku
Thank you for this fun puzzle, TidePool! I liked your first classic a little better since I found it more interesting, but this one was nice as well. Thank you for setting and sharing your classics!

on 19. August 2024, 17:24 by permafrostyx
yay

on 19. August 2024, 13:40 by TidePool
Changed the rating since it only uses one non-standard technique

on 19. August 2024, 13:37 by Niverio
Cute puzzle to practice the fundamentals. It is pretty much a 1-star though, not 3 as you suggested, as all the steps (except the final one) are basic classic techniques. Thank you for setting!