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Marty R.
Joined: 12 Feb 2006 Posts: 5447 Location: Rochester, NY, USA

Posted: Mon Sep 13, 2010 3:47 am Post subject: XYWing limitation 


This topic was initiated by Doyle. W. Rausch. I accidentally deleted it while moving it to this subforum. Sorry Doyle.
Following is what Doyle wrote:
It seems that a unique XYWing solution is not obtained if the 3 XYwing pairs are in a single line (row or column). What misunderstanding of XYWing criteria is involved? Or is this correct? 

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daj95376
Joined: 23 Aug 2008 Posts: 3855

Posted: Mon Sep 13, 2010 3:59 am Post subject: Re: XYWing limitation 


Marty R. wrote:  This topic was initiated by Doyle. W. Rausch. I accidentally deleted it while moving it to this subforum. Sorry Doyle.
Following is what Doyle wrote:
It seems that a unique XYWing solution is not obtained if the 3 XYwing pairs are in a single line (row or column). What misunderstanding of XYWing criteria is involved? Or is this correct?

If you have ZX+XY+YZ in three cells in the same row/column/box, then it's a Naked Triple and any eliminations should have been performed prior to reaching the XYWing technique.
Yes, it's still a Naked Triple if you have ZX+XZY+YZ in three cells of the same house/unit. So the same holds true for an XYZWing. 

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