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David
Joined: 02 Jun 2006
Posts: 58
Location: Bedford, UK
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 Posted: Thu Jun 08, 2006 6:25 pm Post subject: Thursday V Hard puzzle |
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| After filling in 12 relatively simple numbers to todays puzzle, I ended up with 235 and 35 as possibilities for R1C46, and 35 for both R9C46. Does this represent a unique rectangle ? (ie R1C4 has to be a 2) because the rectangle stretches over three blocks rather than two ?? |
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Steve R
Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England
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| Posted: Thu Jun 08, 2006 6:42 pm Post subject: |
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That's it! You are right on all counts.
Steve |
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David
Joined: 02 Jun 2006
Posts: 58
Location: Bedford, UK
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| Posted: Thu Jun 08, 2006 7:44 pm Post subject: |
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| Many thanks, perhaps I am getting the hang of it. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Thu Jun 08, 2006 8:54 pm Post subject: Another solution |
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So far as I know, Sam is not yet publishing puzzles that "need" Unique Rectangles to solve.
This one can also be solved via two X-wings.
David: The constraint is that the corners of the Rectangle occupy only two boxes. That is true here.
Keith
Last edited by keith on Tue Jun 13, 2006 8:51 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: Fri Jun 09, 2006 12:20 am Post subject: |
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| I used an X-Wing and a Type 1 rectangle. Whether either was "needed", I have no idea; I saw them, so I used them. |
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sdtibbs
Joined: 08 May 2006
Posts: 6
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| Posted: Mon Jun 12, 2006 6:09 pm Post subject: |
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I am really trying to understand how you arrive at possibilities of the cell's final number. Could you please explain why r1c4 has to be a two and not a 2 in r2c4. Can you not have 4 cells in the rectangle have the same pair combination ie 35 and if not why.  |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Jun 12, 2006 9:05 pm Post subject: |
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| sdtibbs wrote: | | I am really trying to understand how you arrive at possibilities of the cell's final number. Could you please explain why r1c4 has to be a two and not a 2 in r2c4. Can you not have 4 cells in the rectangle have the same pair combination ie 35 and if not why. |
I don't know anything about the placement of the "2", but as to the last question, the answer is no. This type of thing is a no-no:
| Code: | 35--35
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35--35 |
This is called the "deadly pattern." Published puzzles are supposed to have just one unique solution. If you had the above, you could interchange the "3s" and "5s" and thus the puzzle would have more than one solution.
Keith explains it much better than me in his primer on Rectangles at:
http://www.sudoku.com/forums/viewtopic.php?p=29105#29105 |
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sdtibbs
Joined: 08 May 2006
Posts: 6
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| Posted: Tue Jun 13, 2006 12:48 pm Post subject: |
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lor=darkblue][/color]
Thank you for the link. I have printed it and am studying this. Feel like I am back in school and love learning the process. Hope I can be on my own soon.  |
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