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Oct 10 VH
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Johan



Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium

PostPosted: Fri Oct 12, 2007 8:34 am    Post subject: Reply with quote

Quote:

In your B grid from your second post, you end up with 2 +'s in the same box. If + means = 1, how can this be?


Tracy,

You're right it is deceptive with 2 +'s in the same box, what i really meant is that one of those 2 +'s must be 1 in C6 of that box, when R6C4 has a <->value, which results in a <->value in C6 from box 8.
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Sun Oct 14, 2007 6:42 pm    Post subject: Reply with quote

This is a great puzzle!

You can solve it using only wings as advanced moves. In this order: XY, XYZ, X, XY, XY, and XY.

But, there seem to be lots of ways through this one: I had a Unique X-wing on <18>, a W-wing, a UR, which revealed a swordfish, ...

(Recall: Up to now, all the "Very Hard" puzzles can be solved with only X, XY, and XYZ-wings as "advanced" moves.)

Keith
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TKiel



Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI

PostPosted: Sun Oct 14, 2007 7:51 pm    Post subject: Reply with quote

sdq_pete wrote:
Observing the 12 candidate pairs in blocks 3, 6 and 9, I noticed that whatever value R9C7 took, R6C9 must be 1. Intuitively, I suspect this is related to Johan's links. But can anyone identify any further x-moves here?


The pair of <12> cells (r9c7 & r6c9) are part of a W-wing, (strong links on <2>).

Johan,

Now I see. A system to mark grouped coloring has always presented problems for me. I wish there were a better way to do it (when it's not in a W-wing format) because I think it is an under-utilized technique.
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