36+1 ways of relabelling 9 position pattern with a minimum 8 different clues:

All 9 clues 1 way

8 clues with 1 repeated clue value: 1:8 ways+2:7 ways+3:6 ways+4:5 ways+ ... + 8:1way = 36 ways

When we have symmetric puzzles there could be methods to reduce the need to check all 36 ways because you can predict theat some of the re-labelling is isomorphic to re-labelling that was done earlier!

The following are 2 SPW puzzles midway through our re-labelling process

- Code: Select all
`..1..2...........3........4.............4.............6........7...........8..9..`

..1..2...........3........4.............5.............5........7...........8..9..

You can see that they are isomorphic … Relabelling with 5: 4 ways,6: 3 ways,7: 2 ways and 8: 1 way is not needed as they are isomorphic through labelling. That cuts down the number of re-labelling by 10 to 26 ways

With the Extremely fast solver you are using it may make a very small difference. Using my solvers & processor, I have to cut as many corners as possible!

Tarek