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cgordon
Joined: 04 May 2007 Posts: 769 Location: ontario, canada
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Posted: Fri Jul 13, 2007 2:26 pm Post subject: July 13 very hard |
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By my reckoning, a simple x wing on 3's in cols 1 & 9 leaves a 3 in R5C5. But close to the end, the puzzle seizes up. I eventually found an xyz wing on 489 (pivot R7,C7) which got rid of the 8 in R9C7. Couldn't see any other way. |
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David
Joined: 02 Jun 2006 Posts: 58 Location: Bedford, UK
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Posted: Fri Jul 13, 2007 2:31 pm Post subject: |
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Yes, the xyz wing was fairly easy to spot as well because most of the cells were filled in.
All in all a fairly easy 'very hard'. |
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LloydB
Joined: 09 Jul 2007 Posts: 21 Location: Skagit Co., WA USA
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Posted: Fri Jul 13, 2007 5:23 pm Post subject: |
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Apparently lots of ways to solve this one.
I used an XY-wing, the the X-wing noted and a different XYZ-wing.
A fun one. |
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George Woods
Joined: 28 Mar 2006 Posts: 304 Location: Dorset UK
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Posted: Sat Jul 14, 2007 7:53 am Post subject: Don't need the X wing |
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'cos the x-wing is contained in two boxes the effect of the x wing can be achieved by noting the 3's in box 4 are locked in col 1 and 3's in box 6 are locked in col 9 hence the only place for a 3 in row 5 is r5c5 ....
So we don't need the X-wing !
Incidentally is my use of the word "locked" correct? or should it be described differently? |
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