The New Sudoku Players' Forum

[Mathimagics]

Oh tarek, what a wag!

Ok, plus whether your specs have a contradiction. This is getting rather Python-esque, like, what have the Romans ever done for us?

[Mathimagics]

Sudoku + Forbidden Pairs

FP = 15 26 27 28 29 39 47 59 69

SFP3C.png (3.58 KiB) Viewed 1265 times

This is one of 3 possible 2-clue puzzles for this FP:

2-clue puzzles: Show

Code: Select all

..............8.................9................................................
..............8.......9..........................................................
....5.7..........................................................................


Solution: Show

Code: Select all

412356789975248631863197524356789412248631975197524863789412356631975248524863197

The FP list is interesting, for 2 digits (2 and 9) there are 4 FPs, so there are only 4 allowed neighbours for those values. These are strong constraints.

[SCLT]

Reviving this old thread... I had been independently researching NC puzzles over the last week or so (with 1 and 9 _not_ being considered consecutive). I have some results which confirm those appearing in this thread, and some new results about minimal puzzles.

- There are 5,287,048 valid NC grids
- There are 330,845 non-isomorphic valid NC grids
- There are 809 non-isomorphic NC grids with at least one symmetry

- There are no 3-clue NC puzzles

- There are 609,032 4-clue NC puzzles
- There are 38,065 non-isomorphic 4-clue NC puzzles
- There is exactly one 4-clue symmetric NC puzzle: .................................3...4.....6...7.................................

[Mathimagics]

Reviving this old thread ...

Seems that 6 months is a long time in Sudoku topics ...

Thanks for those NC result confirmations, these are always gratefully accepted (and respected) ...