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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Tue Jan 25, 2011 10:57 pm Post subject: Puzzle 11/01/25 two-fer |
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| Code: | +-----------------------+
| 4 1 . | 8 . . | 9 2 . |
| 8 9 . | 1 . . | . . . |
| . . 3 | . . . | . . . |
|-------+-------+-------|
| 1 7 . | 5 8 . | . . . |
| . . . | 7 . 3 | . . . |
| . . . | . 9 1 | 2 7 . |
|-------+-------+-------|
| 6 . . | . . 4 | 8 . . |
| 7 . . | . . 8 | . . 4 |
| . . . | . . . | . 3 9 |
+-----------------------+
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Wed Jan 26, 2011 11:09 pm Post subject: |
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| Code: |
+--------------+---------------+--------------+
| 4 1 567 | 8 356 567 | 9 2 356 |
| 8 9 2567 | 1 2356 2567 | 3456 456 356 |
| 25 256 3 | 246 2456 9 | 1 8 7 |
+--------------+---------------+--------------+
| 1 7 246 | 5 8 26 | 346 9 36 |
| 9 2468 2468 | 7 246 3 | 456 456 1 |
| 3 456 456 | 46 9 1 | 2 7 8 |
+--------------+---------------+--------------+
| 6 35 19 | 39 7 4 | 8 15 2 |
| 7 235 19 | 39 25 8 | 56 156 4 |
| 25 48 48 | 26 1 256 | 7 3 9 |
+--------------+---------------+--------------+
|
Play this puzzle online at the Daily Sudoku site
I've messed this up twice already and have no idea if I've made simple mechanical errors or logical errors. I have questions about a loop.
Note the XY-Loop that starts with a 6 in r9c4, goes up c4, then over to r3c1 and ends with a 2 in r9c1. I know I can remove the 2 from r9c6.
I also want to remove the 6 from r3c4 and 2s from r3c25. Are these OK? |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Wed Jan 26, 2011 11:37 pm Post subject: |
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| Marty R. wrote: | | Code: |
+--------------+---------------+--------------+
| 4 1 567 | 8 356 567 | 9 2 356 |
| 8 9 2567 | 1 2356 2567 | 3456 456 356 |
| 25 256 3 | 246 2456 9 | 1 8 7 |
+--------------+---------------+--------------+
| 1 7 246 | 5 8 26 | 346 9 36 |
| 9 2468 2468 | 7 246 3 | 456 456 1 |
| 3 456 456 | 46 9 1 | 2 7 8 |
+--------------+---------------+--------------+
| 6 35 19 | 39 7 4 | 8 15 2 |
| 7 235 19 | 39 25 8 | 56 156 4 |
| 25 48 48 | 26 1 256 | 7 3 9 |
+--------------+---------------+--------------+
|
I've messed this up twice already and have no idea if I've made simple mechanical errors or logical errors. I have questions about a loop.
Note the XY-Loop that starts with a 6 in r9c4, goes up c4, then over to r3c1 and ends with a 2 in r9c1. I know I can remove the 2 from r9c6.
I also want to remove the 6 from r3c4 and 2s from r3c25. Are these OK? |
I don't see anything resembling an XY-Loop in your cells. What I do see is an X-Wing.
| Code: | c14 X-Wing <> 2 r3c25,r9c6
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Wed Jan 26, 2011 11:57 pm Post subject: |
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I didn't reach a point of checking for X-Wings. As to the XY-Loop, maybe I'm mis-defining them.
R9c4=6-->r6c4=4-->r3c4=2-->r3c1=5-->r9c1=2.
I wanted to eliminate the 6 and the 2s based on my interpretation (or misinterpretation) of something you told me in another thread awhile back:
"* Look at each assignment and its corresponding elimination(s) in the loop.
* Delete that value from any cells that see the assignment and elimination cells." |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Thu Jan 27, 2011 4:05 am Post subject: |
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Marty,
If you check this message, you'll see that you made the same mistake in this puzzle. There is a distinction between a chain and a network, and you crossed the line into "network" when you derived r3c4=2.
An XY-Loop looks exactly like an XY-Chain -- except the starting cell can "see" the ending cell. When this happens, multiple eliminations become possible. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Jan 27, 2011 4:40 am Post subject: |
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| Danny, thank you. |
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