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Puzzle solvable with another w-wing variation

 
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ravel



Joined: 21 Apr 2006
Posts: 536
PostPosted: Mon Feb 18, 2008 4:58 pm    Post subject: Puzzle solvable with another w-wing variation Reply with quote
Code:
 1 . . | . 2 . | . . 3
 . 4 . | . . . | . 5 .
 . . 5 | . 6 . | 4 . .
 - - - + - - - + - - -
 . . . | 6 . 3 | . . .
 7 . 8 | . . . | 9 . 1
 . . . | 1 . 7 | . . .
 - - - + - - - + - - -
 . . 9 | . 4 . | 8 . .
 . 5 . | . . . | . 9 .
 8 . . | . 3 . | . . 7 TTHsieh

Another w-wing variation i already mentioned somewhere is following.

When you notice pairs ab and ac in a unit, you can look, if you find a pair bc somewhere.

In this case a strong link for b, that connects ab and bc says, that either ac or bc must be c.
Or a strong link for c, that connects ac and bc says, that either ab or bc must be b.

Using it, this puzzle can be solved soon, even without the x-wing. I only saw 2 possible (ab/ac)-candidates with an existing bc-pair, so i could check for it quickly.
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Earl



Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
PostPosted: Mon Feb 18, 2008 6:09 pm    Post subject: w-wing Reply with quote
An xy-chain from R2C6 to R3C9 eliminates 9 from R3C6 and solves the puzzle.

Earl
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Mon Feb 18, 2008 6:55 pm    Post subject: Reply with quote
Quote:
When you notice pairs ab and ac in a unit, you can look, if you find a pair bc somewhere.

In this case a strong link for b, that connects ab and bc says, that either ac or bc must be c.
Or a strong link for c, that connects ac and bc says, that either ab or bc must be b.

Ravel, I want to make sure I understand this. Your first sentence seems to describe an XY-Wing. In my example, your abc = my 123.

Code:

+--------+-------+--------+
| . . .  | . . . | .  . . |
| . . .  | . . . | .  . . |
| . . .  | . . . | .  . . |
+--------+-------+--------+
| . . .  | . . . | .  . . |
| . . .  | . . . | 23 . . |
| . . .  | . . . | .  . . |
+--------+-------+--------+
| . . .  | . . . | .  . . |
| . . .  | . . . | .  . . |
| . . 12 | . . . | 13 . . |
+--------+-------+--------+

Play this puzzle online at the Daily Sudoku site

In your second sentence about a strong link for b connecting ab and bc, that means cell r5c3 comes into play, right?

But in your third sentence about a strong link for c connecting ac and bc, that just means that 3 must be a strong link in column 7.

Am I understanding correctly?
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ravel



Joined: 21 Apr 2006
Posts: 536
PostPosted: Mon Feb 18, 2008 8:47 pm    Post subject: Reply with quote
Marty,

i mean something like this:
Code:

+--------+-------+--------+
| . . .  | . . . | .  . . |
| . . .  | . . . | .  . . |
| . . .  | . . . | .  . . |
+--------+-------+--------+
| . . .  | . . . | .  . . |
| . . .  | . 2 . | 23 . . |
| . . .  | . . . | .  . . |
+--------+-------+--------+
| . . .  | . . . | .  . . |
| . . .  | . . . | 13 . . |
| . . 12 | . 2 . | , . . |
+--------+-------+--------+
If you have a strong link for 2 in column 5, then either r8c7 or r9c3 must be 1.
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Mon Feb 18, 2008 10:11 pm    Post subject: Reply with quote
Thanks for clearing that up. I guess I was thinking about the strong links for M-Wings instead.
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
PostPosted: Mon Feb 18, 2008 11:33 pm    Post subject: Reply with quote
Marty, and ravel:

One of my planned projects is to go back in the archives and look at the correspondence between David Bryant and someone_somewhere on their stars and constellations.

At the time, I was a beginner, and understood none of it. But, I suspect they may have been talking about visual patterns to identify chains.

Keith
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