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Earl
Joined: 30 May 2007 Posts: 677 Location: Victoria, KS
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Posted: Mon Mar 15, 2010 3:35 am Post subject: March 15 VH |
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Could not find a single step. Norm?
A Solution: x-wing (1), then xy-wing (179) with pivot at R6C4 eliminates 7 in R5C1
Early Earl
Last edited by Earl on Mon Mar 15, 2010 10:44 pm; edited 1 time in total |
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Marty R.
Joined: 12 Feb 2006 Posts: 5770 Location: Rochester, NY, USA
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Posted: Mon Mar 15, 2010 4:58 am Post subject: |
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I used your first step, but didn't see your second, so I finished with a four-cell XY-Chain. |
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cgordon
Joined: 04 May 2007 Posts: 769 Location: ontario, canada
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Posted: Mon Mar 15, 2010 6:31 pm Post subject: |
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I also did not see Earl's wing
First I knocked off the <7>s in R3/Box 3 with a Type 4 UR 27.
And then used the <7> s in C6 for a kind of double ER. If it’s the bottom <7> in C6, the ER in B4 knocks off the <7> in R1C2. And if it’s top <7> there’s a reverse flip ER using B3 that also eliminates the same <7>.
But as brilliant as that was, it still did not get me very far - and I ain't into chains. Could this be a V VH?
Code: |
+-------+-------+-------+
| . 7 . | . . . | . 7 7 |
| 7 . . | . . 7 | . . 7 |
| 7 7 . | . 7 . | . . . |
+-------+-------+-------+
| . 7 . | . . . | . 7 . |
| 7 . . | . . 7 | 7 . . |
| . 7 . | . 7 . | 7 . . |
+-------+-------+-------+
| . . . | . . . | . . . |
| . . . | . . . | 7 . 7 |
| . . . | . . . | . . . |
+-------+-------+-------+
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[/code][/quote] |
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Wendy W
Joined: 04 Feb 2008 Posts: 144
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Posted: Mon Mar 15, 2010 10:28 pm Post subject: |
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Marty, I did it the same way you did, plus one more step: X-wing on 2, then chain 17, then XY-wing 167.
I'm normally not a big fan of chains either, but for some reason I found this one really easy to follow. |
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Marty R.
Joined: 12 Feb 2006 Posts: 5770 Location: Rochester, NY, USA
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Posted: Mon Mar 15, 2010 11:55 pm Post subject: |
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I tried it again, this time online instead of pencil and paper, and this time I saw the 197 XY-Wing.
This is what I saw after basics and the X-Wing on 1:
Code: |
+------------+------------+-------------+
| 4 157 3 | 2 8 6 | 9 17 57 |
| 167 2 8 | 15 9 17 | 3 4 567 |
| 167 579 69 | 145 457 3 | 127 8 2567 |
+------------+------------+-------------+
| 2 17 46 | 3 46 8 | 5 17 9 |
| 167 3 49 | 459 45 17 | 167 2 8 |
| 8 79 5 | 19 67 2 | 167 3 4 |
+------------+------------+-------------+
| 5 4 2 | 7 1 9 | 8 6 3 |
| 9 6 1 | 8 3 4 | 27 5 27 |
| 3 8 7 | 6 2 5 | 4 9 1 |
+------------+------------+-------------+
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Play this puzzle online at the Daily Sudoku site |
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storm_norm
Joined: 18 Oct 2007 Posts: 1741
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Posted: Thu Mar 18, 2010 3:56 am Post subject: |
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Quote: | Could not find a single step. Norm? |
Code: | +----------------+----------------+---------------+
| 4 157 3 | 2 8 6 | 9 17 57 |
| 167 2 8 | 15 9 17 | 3 4 567 |
| 167 1579 69 | 145 457 3 | 127 8 2567 |
+----------------+----------------+---------------+
| 2 17 46 | 3 467 8 | 5 17 9 |
| 167 3 469 | 1459 4567 17 | 167 2 8 |
| 8 179 5 | 19 67 2 | 167 3 4 |
+----------------+----------------+---------------+
| 5 4 2 | 7 1 9 | 8 6 3 |
| 9 6 1 | 8 3 4 | 27 5 27 |
| 3 8 7 | 6 2 5 | 4 9 1 |
+----------------+----------------+---------------+ |
the x-wing can be used as part of the fin for the xy-wing.
either the xy-wing {179} is true => r6c5 <> 7
or
(1)r6c1 - (1)r4c2 = (1)r4c8 - (1)r1c8 = (1)r1c2 - (1)r23c1 = (1)r5c1 - (1=7)r5c6
either way the 7 in r5c6 is true and the 7 in r6c5 is toast.
x-wing in red |
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tlanglet
Joined: 17 Oct 2007 Posts: 2468 Location: Northern California Foothills
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Posted: Fri Mar 19, 2010 1:48 pm Post subject: |
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storm_norm wrote: | Quote: | Could not find a single step. Norm? |
Code: | +----------------+----------------+---------------+
| 4 157 3 | 2 8 6 | 9 17 57 |
| 167 2 8 | 15 9 17 | 3 4 567 |
| 167 1579 69 | 145 457 3 | 127 8 2567 |
+----------------+----------------+---------------+
| 2 17 46 | 3 467 8 | 5 17 9 |
| 167 3 469 | 1459 4567 17 | 167 2 8 |
| 8 179 5 | 19 67 2 | 167 3 4 |
+----------------+----------------+---------------+
| 5 4 2 | 7 1 9 | 8 6 3 |
| 9 6 1 | 8 3 4 | 27 5 27 |
| 3 8 7 | 6 2 5 | 4 9 1 |
+----------------+----------------+---------------+ |
the x-wing can be used as part of the fin for the xy-wing.
either the xy-wing {179} is true => r6c5 <> 7
or
(1)r6c1 - (1)r4c2 = (1)r4c8 - (1)r1c8 = (1)r1c2 - (1)r23c1 = (1)r5c1 - (1=7)r5c6
either way the 7 in r5c6 is true and the 7 in r6c5 is toast.
x-wing in red |
Norm, I just got around to looking at your post and am having a problem following your logic.
I see a finned xy-wing condition with vertex 79 in r6c2, pincer 17 in r4c2, pincer 19 in r6c4 and fin 1 in r6c2. However I do not see how the xy-wing forces r5c6=7.
Also, the AIC for the fin may have a typo since is starts in cell r6c1 rather than r6c2.
Ted |
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