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David
Joined: 02 Jun 2006
Posts: 58
Location: Bedford, UK
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 Posted: Thu Aug 30, 2007 9:27 am Post subject: Aug 30 VH |
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| One set of strong links on 3's and an xy wing in blocks 8 and 9 solved the puzzle for me. |
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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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| Posted: Thu Aug 30, 2007 10:32 am Post subject: |
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| An xyz-wing with pivot in R7C4, eliminating <8> in R7C5, opened the puzzle for me. |
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sdq_pete
Joined: 30 Apr 2007
Posts: 119
Location: Rotterdam, NL
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| Posted: Thu Aug 30, 2007 3:34 pm Post subject: |
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Well, the XY wing with pivot 48 at R7C5 and eliminating 9 at R9C8 opened the end game for me:
| Code: |
+-------------+-----------+----------------+
| 6 4 2 | 7 9 5 | 1 8 3 |
| 5 79 78 | 3 1 28 | 2469 469 69 |
| 389 1 38 | 4 6 28 | 29 5 7 |
+-------------+-----------+----------------+
| 7 3 6 | 5 48 49 | 89 2 1 |
| 1 8 9 | 6 2 7 | 5 3 4 |
| 4 2 5 | 89 3 1 | 7 69 689 |
+-------------+-----------+----------------+
| 2 5 3478 | 189 48 6 | 3489 1479 89 |
| 89 79 478 | 189 5 3 | 4689 14679 2 |
| 38 6 1 | 2 7 49 | 38 49 5 |
+-------------+-----------+----------------+
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Play this puzzle online at the Daily Sudoku site
Peter |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Aug 30, 2007 5:18 pm Post subject: |
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| The one XY-Wing did it for me, but I used r7c9 as the pivot, same result. |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Thu Aug 30, 2007 9:04 pm Post subject: |
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| Simple coloring on 8 or 9 or multi-coloring on 8. |
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jLo
Joined: 30 Apr 2007
Posts: 55
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| Posted: Fri Aug 31, 2007 2:56 am Post subject: |
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| I prefer the W-wing on <89>s that solves R9C6. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Fri Aug 31, 2007 1:24 pm Post subject: |
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| Unless I made a lucky error somewhere, I was able to finish with nothing more complex than a simple skyscraper on 8's (C59) which took out the 8 in R4C7. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Aug 31, 2007 3:43 pm Post subject: |
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Craig, I don't see where you made any error. Your skyscraper is one more way to accomplish the same that the XY-Wing does.
| Quote: | | I prefer the W-wing on <89>s that solves R9C6. |
Jlo, are you working from Pete's grid posted above? I'm not seeing how r9c6 gets solved that way. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Fri Aug 31, 2007 4:31 pm Post subject: |
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| Marty: I guess skyscrapers do accomplish the same as xy wings (probably chains also) - but I see them as much different means of identification - using patterns rather than numbers - and so much easier to identify. In fact I failed to spot the xy wings here. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Aug 31, 2007 5:15 pm Post subject: |
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| cgordon wrote: | | Marty: I guess skyscrapers do accomplish the same as xy wings (probably chains also) - but I see them as much different means of identification - using patterns rather than numbers - and so much easier to identify. In fact I failed to spot the xy wings here. |
Craig, I don't think skyscrapers always accomplish the same, it's just in this case the elimination was in the same chain. I think much of the reason that so many techniques can be found is due to people looking for the techniques that they enjoy and that we approach a puzzle with different sequences of steps.
For example, in my case, after the preliminary stuff, and eliminating what I can with basic techniques, I look for XY, XYZ, W, and rectangles. After that's exhausted, I look for X-Wings and skyscrapers, which I don't particularly enjoy.
Just guessing here, but Tracy, who is an excellent solver, has written extensively about coloring in the time I've known him here. (Actually, Tracy is a gender-neutral name and I've just assumed he's a "he"  ). So I don't think it's a coincidence that he spotted the coloring. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Fri Aug 31, 2007 6:39 pm Post subject: |
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| Marty: That's interesting! I've been looking for xy wings once reaching the VH stage - but got a bit bored with them. I tried W wings but they hurt. So I've been looking for alternate solutions like skyscrapers, URs and ERs - which for me are a more satisfying catch - though they don't seem to pop up so often. You'll hear when I find the next one though !! |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Fri Aug 31, 2007 7:44 pm Post subject: |
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| Marty R. wrote: | | I think much of the reason that so many techniques can be found is due to people looking for the techniques that they enjoy and that we approach a puzzle with different sequences of steps. |
I think this is exactly right, except I would substitute "enjoy/find-easy-to-spot".
| Marty R. wrote: | | ...in my case, after the preliminary stuff...I look for XY, XYZ, W, and rectangles. After that's exhausted, I look for X-Wings and skyscrapers... |
I'm just the opposite, as Marty R. guessed. And many times the looking for strong links doesn't wait until after all the preliminary stuff, which is probably why I've ceased thinking of it as an advanced technique. |
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David
Joined: 02 Jun 2006
Posts: 58
Location: Bedford, UK
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| Posted: Fri Aug 31, 2007 9:02 pm Post subject: |
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Just to 'stick my oar in' here, I am with Tracy in that I find looking for strong links a more instinctive technique than many of the others - perhaps I enjoy it more as well.
Anyway, it's great to get a puzzle with so many possible solving options - something for everyone eh ? |
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Glassman
Joined: 21 Oct 2005
Posts: 50
Location: England
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| Posted: Fri Sep 07, 2007 5:46 am Post subject: |
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| cgordon wrote: | | Unless I made a lucky error somewhere, I was able to finish with nothing more complex than a simple skyscraper on 8's (C59) which took out the 8 in R4C7. |
cgordon — Thanks for introducing me to skyscrapers. Beautiful and elegant, and, most important, easy to find.
I solved this one with the key xy-wing on pivot r7c5, but after a lot more basic elimination cleared the way to:-
| Code: |
+------------+-----------+--------------+
| 6 4 2 | 7 9 5 | 1 8 3 |
| 5 79 78 | 3 1 28 | 249 469 69 |
| 389 1 38 | 4 6 28 | 29 5 7 |
+------------+-----------+--------------+
| 7 3 6 | 5 48 49 | 89 2 1 |
| 1 8 9 | 6 2 7 | 5 3 4 |
| 4 2 5 | 89 3 1 | 7 69 689 |
+------------+-----------+--------------+
| 2 5 378 | 189 48 6 | 3489 17 89 |
| 89 79 4 | 18 5 3 | 6 17 2 |
| 38 6 1 | 2 7 49 | 38 49 5 |
+------------+-----------+--------------+
|
Play this puzzle online at the Daily Sudoku site
Glassman  |
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