## help in solving a difficult sudoku

Advanced methods and approaches for solving Sudoku puzzles
sorry then
Wolfgang

Posts: 208
Joined: 22 June 2005

SteveF wrote:It is then possible to eliminate 6 from r3c5 based on colours, using the chain r6c5, r6c9, r4c7, r3c7).

Found it now, but can you explain this step, please?
Ooh, bad day, its easy, excuse me again
Wolfgang

Posts: 208
Joined: 22 June 2005

Steve,

Thank you for that !
After having tried and tested the 6's swordfish, I can finally find the logic in the method you proposed to finishing the puzzle !

I did not know that such a combination of swordfish could exist, I had previously understood that 2 or 3 digit possibilities in a single row/column must have EACH a corresponding possibility in column/row, before a swordfish could exist and only then eliminate all other possibilities of those rows and columns.

In this case, I thought that r1c4 must have been a part of the swordfish for their to be a swordfish in the first place ! -- which is why I could not see a visible swordfish - but now I know differently !!

Yet again -- something new learnt !!
hana somekh

Posts: 28
Joined: 30 July 2005

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