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April 13 VH

 
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Clement



Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania

PostPosted: Tue Apr 13, 2010 12:45 am    Post subject: April 13 VH Reply with quote

XY-Wing 24 27 47 eliminates 4 in r3c1 solves the puzzle.
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Toole130



Joined: 05 Feb 2010
Posts: 3

PostPosted: Tue Apr 13, 2010 11:04 pm    Post subject: Reply with quote

I noticed the connection of 45 (R3C1) to 24 (R3C9) to 27 (R7C9) to 47 (R7C1). I did not know what to call it or how to pick out the number to be eliminated. I just chose 4 for R3C1, went around the loop, and found this would not work. So this cell must be 5. Is there a more sophisticated way to arrive at which cell is the "odd" cell? Is it the one containing a number that is not in the other 3 cells?

Bart
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Wed Apr 14, 2010 12:05 am    Post subject: Reply with quote

What you have is an XY-Wing, the one that Clement mentioned. The basic rule of this technique is you start with a cell we'll call XY. That cell must see both a cell we'll call XZ and YZ. Any cell(s) that see both XZ and YZ cannot be Z.

XY = 27
XZ = 24
YZ = 47

Since r3c1 sees both the 24 and 47 it cannot contain a 4.

Hope this helps, ask away if necessary.
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Wendy W



Joined: 04 Feb 2008
Posts: 144

PostPosted: Thu Apr 15, 2010 12:29 am    Post subject: Reply with quote

Nice XY-planation, Marty!
I used Clement's XY-wing but first I needed another XY-wing, 278.
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