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Sept 1 VH

 
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Johan



Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium

PostPosted: Sat Sep 01, 2007 10:59 am    Post subject: Sept 1 VH Reply with quote

One move and the puzzle collapses,

This is the grid after basic eliminations

Code:

+-------------+--------------+------------+
| 36  48   9  | 67  48   1   | 2  5   37  |
| 478 2    5  | 3   4789 78  | 1  789 6   |
| 136 678  17 | 679 5    2   | 4  789 379 |
+-------------+--------------+------------+
| 9   5    8  | 4   37   37  | 6  2   1   |
| 126 67   17 | 8   26   9   | 5  3   4   |
| 26  3    4  | 1   26   5   | 79 79  8   |
+-------------+--------------+------------+
| 478 4789 3  | 5   1    678 | 79 46  2   |
| 5   789  6  | 2   78   4   | 3  1   79  |
| 47  1    2  | 79  379  367 | 8  46  5   |
+-------------+--------------+------------+

www.dailysudoku.com/sudoku/play
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David



Joined: 02 Jun 2006
Posts: 58
Location: Bedford, UK

PostPosted: Sat Sep 01, 2007 11:40 am    Post subject: Reply with quote

I used the UR. I dare say there are several other options to solve it and I will have a look again at the puzzle after my Saturday chores are finished !
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cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Sat Sep 01, 2007 12:39 pm    Post subject: Reply with quote

A most excellent Sudoku - UR Heaven!! I used 3 URs including a Type 3 (I think) with 4 cells and 5 candidates. So OK - there may have been an easier way - but my solution had flair and panache.
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sdq_pete



Joined: 30 Apr 2007
Posts: 119
Location: Rotterdam, NL

PostPosted: Sat Sep 01, 2007 12:42 pm    Post subject: Reply with quote

I guess that Johan means the XYZ wing with pivot at R9C5, though I too initially saw the UR.

Peter
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Earl



Joined: 30 May 2007
Posts: 615
Location: Victoria, KS

PostPosted: Sat Sep 01, 2007 3:54 pm    Post subject: Sept 1 VH Reply with quote

I saw an unusal UR of 26 with a phanton candidate cell of 17. Couldn't resist, since I never used it before. But I had to use two w-wings later. The xyz-wing is easier.

Earl
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Johan



Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium

PostPosted: Sat Sep 01, 2007 10:22 pm    Post subject: Reply with quote

The xyz-wing Peter mentioned, with pivot in R9C5 solved the puzzle in one move for me.

There are some other techniques like UR Type 1, which eliminates [26] in R5C1 => R5C1=1

Type 4 UR (according to the Sudopedia site), in R49C56 avoiding the deadly [37] pattern, R9C5=9 or R9C6=6, eliminating both <7>'s in these two cells.

Being a pencil and paper solver the xyz-wing was the first eye-catcher for me, collapsing the whole puzzle.

Like George noted in a previous post, many ways to skin the cat

but lesser pain if you can do it in one time (for the cat of course) Smile
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jambar



Joined: 05 Sep 2007
Posts: 2
Location: Australia

PostPosted: Mon Sep 10, 2007 12:24 am    Post subject: UR Reply with quote

I'm new to this forum, but have been solving sudokus for a while (paper and pen only). Can anybody please explain what does UR stand for and where do I find any explanation? I've checked sudopedia but didn't find it there.
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TKiel



Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI

PostPosted: Mon Sep 10, 2007 1:30 am    Post subject: Reply with quote

Unique Rectangle.

You can follow this link for more information.
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jambar



Joined: 05 Sep 2007
Posts: 2
Location: Australia

PostPosted: Mon Sep 10, 2007 2:02 am    Post subject: Reply with quote

Thanks, Tracy. I guess I have been using UR type 1, but have to study the other types. Very interesting!
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Glassman



Joined: 21 Oct 2005
Posts: 50
Location: England

PostPosted: Tue Sep 18, 2007 9:22 am    Post subject: Re: Sept 1 VH Reply with quote

I got as far as Johan's step at the start of this topic, and then noticed a very obvious x-wing on 8s in rows 1 and 8, which simplified the puzzle considerably, and placed the 8 in box 3:-

Code:

+-----------+------------+----------+
| 36  48 9  | 67 48  1   | 2  5  37 |
| 48  2  5  | 3  479 78  | 1  79 6  |
| 136 67 17 | 69 5   2   | 4  8  39 |
+-----------+------------+----------+
| 9   5  8  | 4  37  37  | 6  2  1  |
| 126 67 17 | 8  26  9   | 5  3  4  |
| 26  3  4  | 1  26  5   | 79 79 8  |
+-----------+------------+----------+
| 478 49 3  | 5  1   678 | 79 46 2  |
| 5   89 6  | 2  78  4   | 3  1  79 |
| 47  1  2  | 79 379 367 | 8  46 5  |
+-----------+------------+----------+

Play this puzzle online at the Daily Sudoku site.

Nevertheless it still required the key xyz-wing on pivot r9c5 to finish the puzzle.

Glassman Cool
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