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Feb 23 VH

 
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Earl



Joined: 30 May 2007
Posts: 677
Location: Victoria, KS

PostPosted: Mon Feb 23, 2009 3:02 am    Post subject: Feb 23 VH Reply with quote

An xy-wing (245) does it.

Early Earl
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Mon Feb 23, 2009 4:06 am    Post subject: Reply with quote

I decided not to look for xy-wings since the last several puzzles seem to fall to a single one. Instead I looked for w-wings and the first one I found still completed the puzzle.
Quote:
w-wing <24> at r1c8 & r4c7 with strong link <2> in row <8>. Transport <4> from r4c7 => r4c9 => r7c9; delete <4> r78c8.

Ted Rolling Eyes
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crunched



Joined: 05 Feb 2008
Posts: 168

PostPosted: Mon Feb 23, 2009 6:16 am    Post subject: Reply with quote

Here are the basics per my handiwork.
As Earl reports, a 24-25-45 xy wing does it.
I am terrible at seeing where the w-wings lurk.
I bet some of you chain-gangers find various
chain solutions here.

Code:

+----------+------------+-------------+
| 25  9 47 | 578 578 1  | 3   245  6  |
| 6   3 47 | 2   9   57 | 45  1    8  |
| 258 1 28 | 6   4   3  | 9   7    25 |
+----------+------------+-------------+
| 3   5 9  | 17  17  8  | 24  6    24 |
| 7   8 6  | 59  2   4  | 1   59   3  |
| 12  4 12 | 3   6   59 | 8   59   7  |
+----------+------------+-------------+
| 148 2 5  | 79  3   79 | 6   48   14 |
| 148 7 3  | 158 158 6  | 245 2458 9  |
| 9   6 18 | 4   158 2  | 7   3    15 |
+----------+------------+-------------+

Play this puzzle online at the Daily Sudoku site
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Mon Feb 23, 2009 7:13 am    Post subject: Reply with quote

Quote:
I bet some of you chain-gangers find various
chain solutions here.



like this one that doesn't really help, but could be of some help in a more difficult puzzle.

Code:
.---------------.---------------.---------------.
| 25   9    47  |U578 U578  1   | 3    24   6   |
| 6    3    47  | 2    9   *57  |*45   1    8   |
| 258  1    28  | 6    4    3   | 9    7    25  |
:---------------+---------------+---------------:
| 3    5    9   | 17   17   8   | 24   6    24  |
| 7    8    6   | 59   2    4   | 1    59   3   |
| 12   4    12  | 3    6    59  | 8    59   7   |
:---------------+---------------+---------------:
| 148  2    5   | 79   3    79  | 6    48   14  |
| 148  7    3   |U158 U158  6   |*245  248  9   |
| 9    6    18  | 4   -158  2   | 7    3   *15  |
'---------------'---------------'---------------'

the UR on {5,8} in r18c45 says that neither the 1's in r8c45 or the 5's in r1c45 can both be false.
creates this strong inference...
UR58[(1)r8c45 = (7)r1c45]...

can be extended into this chain...
UR58[(1)r8c45 = (7)r1c45] - (7=5)r2c6 - (5)r2c7 = (5)r8c7 - (5=1)r9c9; r9c5 <> 1
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George Woods



Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK

PostPosted: Mon Feb 23, 2009 10:25 pm    Post subject: another xy or w wing wilk do! Reply with quote

crunched wrote:
Here are the basics per my handiwork.
As Earl reports, a 24-25-45 xy wing does it.
I am terrible at seeing where the w-wings lurk.
I bet some of you chain-gangers find various
chain solutions here.

Code:

+----------+------------+-------------+
| 25  9 47 | 578 578 1  | 3   245  6  |
| 6   3 47 | 2   9   57 | 45  1    8  |
| 258 1 28 | 6   4   3  | 9   7    25 |
+----------+------------+-------------+
| 3   5 9  | 17  17  8  | 24  6    24 |
| 7   8 6  | 59  2   4  | 1   59   3  |
| 12  4 12 | 3   6   59 | 8   59   7  |
+----------+------------+-------------+
| 148 2 5  | 79  3   79 | 6   48   14 |
| 148 7 3  | 158 158 6  | 245 2458 9  |
| 9   6 18 | 4   158 2  | 7   3    15 |
+----------+------------+-------------+

Play this puzzle online at the Daily Sudoku site


If you eliminate the 5s in col 8 boxes 3 and 9, ('cos of the 59s in box6),you will get both the 245 xy wing and the w-wing on 24 (acting on 2s in col9)

This is the third V Hard that has had an xy wing and w wing at the same stage albeit this time the subsequent moves converge about 6 moves later, rather than the one or two in the two previous v hard!
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Wendy W



Joined: 04 Feb 2008
Posts: 144

PostPosted: Mon Feb 23, 2009 11:08 pm    Post subject: Reply with quote

"Chain-gangers" -- great term! Well coined, "Crunched."
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crunched



Joined: 05 Feb 2008
Posts: 168

PostPosted: Tue Feb 24, 2009 12:45 am    Post subject: Reply with quote

Wendy W wrote:
"Chain-gangers" -- great term! Well coined, "Crunched."


Thanks. Of course, the sound (per Sam Cooke) of the men working on the chain...goes totally well with sudoku.
Here:
http://music.yahoo.com/track/1370054
Click player where it says "chain gang" right above where it says Sam Cooke.

Or:

http://www.last.fm/music/Sam+Cooke/_/Chain+Gang
Click player in upper right area of page, where it says "Sam Cooke Chain Gang"
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stevieboy



Joined: 25 Jan 2008
Posts: 31
Location: Michigan

PostPosted: Tue Feb 24, 2009 4:57 pm    Post subject: Reply with quote

I'm looking all around for the 245 xy-wing - usually, I see 'em pretty fast...however, I can't find it here (at least, where I can actually eliminate a common "claw" number). Where is the darn thing? None of the 24-25-45 combinations seem to have a common area, as far as I see...? Hmmm...
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Marty R.



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

PostPosted: Tue Feb 24, 2009 5:46 pm    Post subject: Reply with quote

Stevieboy,

In George's grid above the pivot is in r3c9 and the pincers are in r2c7 and r4c9.
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