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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Mon Apr 23, 2012 8:43 pm Post subject: Free Press April 20, 2012 |
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| Code: | Puzzle: FP042012
+-------+-------+-------+
| . . . | . . 8 | 6 . . |
| . . . | . . . | . 1 9 |
| 3 . . | . 1 . | . 2 . |
+-------+-------+-------+
| . . . | . 5 . | . 3 . |
| . 2 3 | . . . | 8 5 . |
| . 7 . | . 2 9 | . . . |
+-------+-------+-------+
| . . . | . 6 . | . . 4 |
| 7 9 . | . . . | . . . |
| . . 6 | 2 . 3 | . . . |
+-------+-------+-------+
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Play this puzzle online at the Daily Sudoku site
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Tue Apr 24, 2012 4:11 am Post subject: |
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Tough getting started on this one.
Looked at the 58 UR in boxes 47; common outcome r9c9=1.
Four-cell XY-Chain; r23c7, r8c9<>5
W-Wing (45), SL 5 in c2; r2c1<>4 -or- BUG+2 |
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DonM
Joined: 15 Sep 2009
Posts: 51
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| Posted: Tue Apr 24, 2012 6:52 pm Post subject: |
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(ER=7.2) After basics (which in this case is also the SSTS position):
| Code: | *--------------------------------------------------------------------*
| 1245 145 12459 | 45 39 8 | 6 7 35 |
| 4568 4568 4578 | 456 37 2 | 345 1 9 |
| 3 456 79 | 79 1 456 | 45 2 8 |
|----------------------+----------------------+----------------------|
| 146 146 14 | 8 5 7 | 9 3 2 |
| 9 2 3 | 16 4 16 | 8 5 7 |
| 58 7 58 | 3 2 9 | 1 4 6 |
|----------------------+----------------------+----------------------|
| 1258 3 1258 | 79 6 15 | 257 89 4 |
| 7 9 125 | 145 8 145 | 235 6 135 |
| 1458 1458 6 | 2 79 3 |-57 89 15 |
*--------------------------------------------------------------------*
als(45=3)r34c7-(3=7)r2c5-(7=9)r9c5-(8=9)r9c8-als(8=145)r9c12/r9c9 -> r9c7=7 -> many singles |
| Code: |
*--------------------------------------------------*
| 2 1 9 | 4 3 8 | 6 7 5 |
| 456 8 *45 | 56 7 2 | 3 1 9 |
| 3 *56 7 | 9 1 56 | 4 2 8 |
|----------------+----------------+----------------|
| 146 *46 1-4 | 8 5 7 | 9 3 2 |
| 9 2 3 | 16 4 16 | 8 5 7 |
| 58 7 58 | 3 2 9 | 1 4 6 |
|----------------+----------------+----------------|
| 18 3 128 | 7 6 15 | 25 9 4 |
| 7 9 12 | 15 8 4 | 25 6 3 |
| 45 45 6 | 2 9 3 | 7 8 1 |
*--------------------------------------------------*
xy-wing as shown -> r4c3<>4=1
stte |
(It's possible that a simpler chain could replace the first one, but this is a first thought.) |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Tue Apr 24, 2012 8:02 pm Post subject: |
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I'm revising my solution. The four-cell XY-Chain ABCD was available right off the bat and there was no W-Wing on 45 or BUG+2 left after cleanup.
| Code: | *-----------------*-------------*------------- -*
| 1245 145 12459 | 45 C39 8 | 6 7 D35 |
| 4568 4568 4578 | 456 37 2 | 345 1 9 |
| 3 456 79 | 79 1 456 | 45 2 8 |
+-----------------+-------------+------------- -+
| 146 146 14 | 8 5 7 | 9 3 2 |
| 9 2 3 | 16 4 16 | 8 5 7 |
| 58 7 58 | 3 2 9 | 1 4 6 |
+-----------------+-------------+---------------+
| 1258 3 1258 | 79 6 15 | 257 89 4 |
| 7 9 125 | 145 8 145 | 235 6 13-5 |
| 1458 1458 6 | 2 B79 3 | A57 89 1-5 |
+-----------------+------------+----------------+ |
After the chain the grid was reduced to below, where the XY-Wing (564), pivoted in r3c2 finished things off.
| Code: |
+------------+---------+--------+
| 2 1 9 | 4 3 8 | 6 7 5 |
| 456 8 45 | 56 7 2 | 3 1 9 |
| 3 56 7 | 9 1 56 | 4 2 8 |
+------------+---------+--------+
| 146 46 14 | 8 5 7 | 9 3 2 |
| 9 2 3 | 16 4 16 | 8 5 7 |
| 58 7 58 | 3 2 9 | 1 4 6 |
+------------+---------+--------+
| 18 3 128 | 7 6 15 | 25 9 4 |
| 7 9 12 | 15 8 4 | 25 6 3 |
| 45 45 6 | 2 9 3 | 7 8 1 |
+------------+---------+--------+
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Play this puzzle online at the Daily Sudoku site |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Tue Apr 24, 2012 10:18 pm Post subject: |
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Nice find, Marty !!!
The XY-Chain also forces eliminations r23c7<>5, but you still need the XY-Wing. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Wed Apr 25, 2012 1:44 am Post subject: |
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| daj95376 wrote: | Nice find, Marty !!!
The XY-Chain also forces eliminations r23c7<>5, but you still need the XY-Wing. |
Thanks Danny. I didn't list the other 5s because they will be eliminated as a result of the one I listed.
Is there some general standard about listing all direct eliminations vs. just the minimum necessary? I never know what to list or not list. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Wed Apr 25, 2012 4:25 am Post subject: |
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| Marty R. wrote: | Thanks Danny. I didn't list the other 5s because they will be eliminated as a result of the one I listed.
Is there some general standard about listing all direct eliminations vs. just the minimum necessary? I never know what to list or not list.
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Hello Marty,
I don't think there's a "convention" on what must be listed. I try to list all eliminations that I see because I might miss something ... and others might catch it and let me know. That way, I've learned from a mistake.
However, I know of a few people who only list the "important" eliminations, but I know that they would have see the others as well. I'll add you to this list of people.
Regards, Danny |
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