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Feb 27, 2007

 
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AThiker



Joined: 01 May 2007
Posts: 6
Location: Taipei

PostPosted: Sun May 06, 2007 7:29 am    Post subject: Feb 27, 2007 Reply with quote

Another oldie

+------------+----------+--------------+
| 78 12 3 | 5 14 28 | 2478 9 6 |
| 6 4 9 | 7 3 28 | 1258 258 128 |
| 578 125 18 | 6 14 9 | 2478 248 3 |
+------------+----------+--------------+
| 1 3 57 | 9 57 4 | 28 6 28 |
| 58 9 68 | 1 2 56 | 3 7 4 |
| 4 67 2 | 8 67 3 | 9 1 5 |
+------------+----------+--------------+
| 3 67 57 | 4 568 1 | 258 258 9 |
| 9 15 4 | 2 58 7 | 6 3 18 |
| 2 8 16 | 3 9 56 | 145 45 7 |
+------------+----------+--------------+

The hint is a 7 in r1 c1, but I do not see it.[/list]
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Angel



Joined: 26 Mar 2006
Posts: 31

PostPosted: Mon May 07, 2007 11:05 am    Post subject: Reply with quote

Code:
+------------+----------+--------------+
|  78  12  3 | 5  14 28 | 2478   9   6 |
|   6   4  9 | 7   3 28 | 1258 258 128 |
| 578 125 18 | 6  14  9 | 2478 248   3 |
+------------+----------+--------------+
|   1   3 57 | 9  57  4 |   28   6  28 |
|  58   9 68 | 1   2 56 |    3   7   4 |
|   4  67  2 | 8  67  3 |    9   1   5 |
+------------+----------+--------------+
|   3  67 57 | 4 568  1 |  258 258   9 |
|   9  15  4 | 2  58  7 |    6   3  18 |     
|   2   8 16 | 3   9 56 |  145  45   7 |
+------------+----------+--------------+


xy wing r3c3, r1c2, r1c6 eliminates 8 from r1c1 (to give the hint)

but another xy wing r9c6, r9c3, r8c2 eliminates 5 from r8c5 and cracks the puzzle wide open.

By the way if you put code tags round your grids they are a lot easier to read.
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AThiker



Joined: 01 May 2007
Posts: 6
Location: Taipei

PostPosted: Mon May 07, 2007 12:54 pm    Post subject: Reply with quote

Thanks for the help. For every very hard puzzle I look for those good ol xy wings (and xyz), but sometimes just do not see them.

Still trying to get my grid to line up (see ideas given me on Jan 6 post). Are you saying that you click on code on the post page, then paste the grid? Thx I hate the misaligned grids.
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Angel



Joined: 26 Mar 2006
Posts: 31

PostPosted: Mon May 07, 2007 1:25 pm    Post subject: Reply with quote

I'm not sure where you had your grid to start with, but an easy way to get it to look good is to format it in Notepad. Make sure it looks OK there.

Then open the posting page on the forum, copy and paste your grid from Notepad. Don't worry if it doesn't look OK at this point - this is not how it will look when posted. Highlight the grid, then click the code button. This puts code tags at the start and end of your grid. You can check if it's going to work by using the preview button.

This is what I did to your original grid to make it line up better.
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Marty R.



Joined: 12 Feb 2006
Posts: 5732
Location: Rochester, NY, USA

PostPosted: Mon May 07, 2007 3:41 pm    Post subject: Reply with quote

Quote:
Still trying to get my grid to line up (see ideas given me on Jan 6 post). Are you saying that you click on code on the post page, then paste the grid? Thx I hate the misaligned grids.


See my post on page 2 of the thread, "May 1 VH."
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pbreinhart



Joined: 21 Sep 2007
Posts: 9
Location: Atlanta, GA

PostPosted: Thu Feb 14, 2008 3:40 am    Post subject: pbreinhart Reply with quote

I haven't been able to get to where Angel and ATHiker start even after staring at and thinking about the puzzle for quite awhile. I am here:

Code:

+--------------+-----------+--------------+
| 78  12  3    | 5 14   28 | 2478 9   6   |
| 6   4   9    | 7 3    28 | 1258 258 128 |
| 578 125 158  | 6 14   9  | 2478 248 3   |
+--------------+-----------+--------------+
| 1   3   57   | 9 57   4  | 28   6   28  |
| 58  9   568  | 1 2    56 | 3    7   4   |
| 4   67  2    | 8 67   3  | 9    1   5   |
+--------------+-----------+--------------+
| 3   67  567  | 4 5689 1  | 258  258 79  |
| 9   15  4    | 2 58   7  | 6    3   18  |
| 2   8   1567 | 3 569  56 | 145  45  79  |
+--------------+-----------+--------------+

Play this puzzle online at the Daily Sudoku site

Any help would be greatly appreciated. Thank you.
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Marty R.



Joined: 12 Feb 2006
Posts: 5732
Location: Rochester, NY, USA

PostPosted: Thu Feb 14, 2008 6:13 am    Post subject: Re: pbreinhart Reply with quote

pbreinhart wrote:
I haven't been able to get to where Angel and ATHiker start even after staring at and thinking about the puzzle for quite awhile. I am here:

Code:

+--------------+-----------+--------------+
| 78  12  3    | 5 14   28 | 2478 9   6   |
| 6   4   9    | 7 3    28 | 1258 258 128 |
| 578 125 158  | 6 14   9  | 2478 248 3   |
+--------------+-----------+--------------+
| 1   3   57   | 9 57   4  | 28   6   28  |
| 58  9   568  | 1 2    56 | 3    7   4   |
| 4   67  2    | 8 67   3  | 9    1   5   |
+--------------+-----------+--------------+
| 3   67  567  | 4 5689 1  | 258  258 79  |
| 9   15  4    | 2 58   7  | 6    3   18  |
| 2   8   1567 | 3 569  56 | 145  45  79  |
+--------------+-----------+--------------+

Play this puzzle online at the Daily Sudoku site

Any help would be greatly appreciated. Thank you.

Phil, welcome to the forum. There is an XYZ-Wing, 567, pivoted in r7c3 which takes out the 7 from r9c3. A coloring chain on 5 starting at r9c6 to r5c6 to r4c5 to r4c3 will take out the 5 from r9c3. That gets us here:

Code:
+--------------+-----------+--------------+
| 78  12  3    | 5 14   28 | 2478 9   6   |
| 6   4   9    | 7 3    28 | 1258 258 128 |
| 578 125 158  | 6 14   9  | 2478 248 3   |
+--------------+-----------+--------------+
| 1   3   57   | 9 57   4  | 28   6   28  |
| 58  9   568  | 1 2    56 | 3    7   4   |
| 4   67  2    | 8 67   3  | 9    1   5   |
+--------------+-----------+--------------+
| 3   67  567  | 4 5689 1  | 258  258 79  |
| 9   15  4    | 2 58   7  | 6    3   18  |
| 2   8   16   | 3 569  56 | 145  45  79  |
+--------------+-----------+--------------+


Now in box 7, the 7s are confined to row 7, so the 7 in r7c9 is removed. That sets off a few moves but I don't know how far it can take one.

Good luck.
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Thu Feb 14, 2008 7:01 am    Post subject: Reply with quote

That coloring on <5> is also a Kite. But, even better if you're going for <5>s, you might want to think: Skyscraper.

However, in keeping with the VH idea that only X-, XY- and XYZ-Wings are required, there is an X-Wing in the grid after applying that XYZ-Wing elimination of the <7>. (Hint: It doesn't involve <5>s.) That won't solve the puzzle. But, it opens up an XY-Wing that does.
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pbreinhart



Joined: 21 Sep 2007
Posts: 9
Location: Atlanta, GA

PostPosted: Thu Feb 14, 2008 8:39 pm    Post subject: Reply with quote

Thanks Marty and Asellus. I will do some research on the techniques. I wouldn't have gotten to a solution without the hints.
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