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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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 Posted: Sat Sep 01, 2007 10:59 am Post subject: Sept 1 VH |
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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 |
+-------------+--------------+------------+
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www.dailysudoku.com/sudoku/play |
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David
Joined: 02 Jun 2006
Posts: 58
Location: Bedford, UK
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| Posted: Sat Sep 01, 2007 11:40 am Post subject: |
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| 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
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| Posted: Sat Sep 01, 2007 12:39 pm Post subject: |
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| 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
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| Posted: Sat Sep 01, 2007 12:42 pm Post subject: |
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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: 677
Location: Victoria, KS
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| Posted: Sat Sep 01, 2007 3:54 pm Post subject: Sept 1 VH |
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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
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| Posted: Sat Sep 01, 2007 10:22 pm Post subject: |
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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)  |
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jambar
Joined: 05 Sep 2007
Posts: 2
Location: Australia
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| Posted: Mon Sep 10, 2007 12:24 am Post subject: UR |
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| 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
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| Posted: Mon Sep 10, 2007 1:30 am Post subject: |
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Unique Rectangle.
You can follow this link for more information. |
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jambar
Joined: 05 Sep 2007
Posts: 2
Location: Australia
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| Posted: Mon Sep 10, 2007 2:02 am Post subject: |
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| 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
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| Posted: Tue Sep 18, 2007 9:22 am Post subject: Re: Sept 1 VH |
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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 |
+-----------+------------+----------+
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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  |
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