Projective Forbidden Pairs
(Published on 24. January 2021, 12:52 by LKegel)
An example of a projective row and column and adjacency on a projective plane (traveling up from R6C2 you end up in R5C8, etc.)
The rules:
- The 3x3 boxes contain the digits 1-9 exactly once as usual.
- Every projective row and column contains the digits 1-9 exactly once.
- Two adjacent cells may not contain the following pairs in any ordering: (1,9), (2,3) and (7,8).
Important: Think carefully about when two cells are adjacent on a projective plane. For example, cells separated by a dot may seem to be adjacent, but they are not! Also, it is fine to break the standard rules of sudoku by having repeats in a standard column or row!
f-puzzles link here: here.
Solution code: Column 6 followed by row 5 (of the actual grid, so no projective rows or columns).
Comments
on 26. September 2021, 20:40 by polar
Very nice puzzle but boy did I have to concentrate (and restart a couple of times)! Definitely needed colours on the rows/columns to keep me on track.
Penpa+ link:
https://git.io/JzSjM (no colours)
https://git.io/Jz9em (with colours)
on 25. January 2021, 22:15 by Jviscus
a toughie, but a goodie. well worth the time :)
on 25. January 2021, 13:23 by SirWoezel
If you think this is hard, just wait until setters start combining this ruleset with sandwich sudoku ;)
@SirWoezel Wow that sounds absolutely evil!
on 25. January 2021, 09:33 by LKegel
Added examples of adjacency and changed difficulty to 3/5.
on 25. January 2021, 04:11 by DiMono
I think you have seriously underestimated the difficulty of this puzzle. After almost half an hour I have 6 digits placed. This is easily a 5/5 difficulty.
on 24. January 2021, 21:43 by SirWoezel
Weird. Loads of fun too. But mostly weird.
@SirWoezel I hope that's a compliment ;)
on 24. January 2021, 13:58 by LKegel
Clarified the "forbidden pairs" rule.
on 24. January 2021, 13:31 by LKegel
The example contained an error, this has been fixed.
