Very Hard puzzle

Advanced methods and approaches for solving Sudoku puzzles

Postby Bernard Stay » Mon Apr 18, 2005 2:03 pm

The following "very hard" puzzle is offered on one of the Su Doku software sites:-




I resorted to the "x-wing" technique to solve it, though I don't know whether that was entirely necessary. Perhaps someone else would like to have a go and confirm (or otherwise).
Bernard Stay
Posts: 94
Joined: 22 March 2005

Postby Sue De Coq » Mon Apr 18, 2005 2:47 pm

IMHO, you couldn't do it without an X-Wing (in the 6s).
Sue De Coq
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Joined: 01 April 2005

Postby su_doku » Mon Apr 18, 2005 9:38 pm

Bernard this is the same puzzle which IJ initiated and which brought out the x-wings theory - see under the Times puzzles postings - and in which you participated - your comment below to jog your memory


Bernard Stay

Posted: Tue Mar 29, 2005 6:56 pm Post subject:


Well, (my pennyworth) I can't see any way beyond the position shown.


[I solved it by trying first 7 then 6 in r1c6 - in the latter case it comes out]

I'd be very interested in a true logical solution - if there is one.
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Joined: 19 March 2005

Postby Bernard Stay » Tue Apr 19, 2005 7:56 am

So it is! Silly me, I should have checked.
Bernard Stay
Posts: 94
Joined: 22 March 2005

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