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daj95376
Joined: 23 Aug 2008 Posts: 3854
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Posted: Sun May 10, 2009 6:54 am Post subject: Set XY_02 Puzzle 108 |
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Last puzzle of the set. Solvable as a one-stepper using a 4-cell XY-Chain -- so don't use it.
Code: | +-----------------------+
| 9 6 2 | . . . | 1 3 . |
| 3 8 . | . . . | . 9 . |
| 4 . . | . . 3 | . 5 2 |
|-------+-------+-------|
| . . . | 5 9 . | . . . |
| . . . | 8 . . | 4 6 . |
| . . 6 | . . 4 | . . . |
|-------+-------+-------|
| 6 . . | . 4 . | 5 . . |
| 7 4 9 | . 5 . | . 1 . |
| . . 3 | . . . | . . 6 |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site |
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arkietech
Joined: 31 Jul 2008 Posts: 1834 Location: Northwest Arkansas USA
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Posted: Sun May 10, 2009 12:01 pm Post subject: |
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I used: |
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tlanglet
Joined: 17 Oct 2007 Posts: 2468 Location: Northern California Foothills
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Posted: Sun May 10, 2009 1:36 pm Post subject: |
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My one step solution was a: Quote: | xy-wing 789 with pivot 89 at r9c7 and pseudo-cell 78 in col7 to delete 7 from r12c9.
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Ted |
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daj95376
Joined: 23 Aug 2008 Posts: 3854
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Posted: Sun May 10, 2009 4:28 pm Post subject: |
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tlanglet wrote: | My one step solution was ... |
That matches the 4-cell XY-Chain. |
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tlanglet
Joined: 17 Oct 2007 Posts: 2468 Location: Northern California Foothills
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Posted: Sun May 10, 2009 5:12 pm Post subject: |
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daj95376 wrote: | tlanglet wrote: | My one step solution was ... |
That matches the 4-cell XY-Chain. |
But teacher, I did not cheat on purpose. Do I have to find an alternate solution? Huh Huh ............
Ted |
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daj95376
Joined: 23 Aug 2008 Posts: 3854
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Posted: Sun May 10, 2009 6:01 pm Post subject: |
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tlanglet wrote: | But teacher, I did not cheat on purpose. Do I have to find an alternate solution? Huh Huh ............
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Okay, we'll let it slide this time.
Danny |
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arkietech
Joined: 31 Jul 2008 Posts: 1834 Location: Northwest Arkansas USA
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Posted: Sun May 10, 2009 6:40 pm Post subject: |
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tlanglet wrote: | My one step solution was a... |
Code: | *-----------------------------------------------------------------------------*
| 9 6 2 |*47 #78 5 | 1 3 78-4 |
| 3 8 5 | 127-4 1267 127 | 67 9 *47 |
| 4 17 17 | 9 #68 3 |#68 5 2 |
|-------------------------+-------------------------+-------------------------|
| 128 1237 4 | 5 9 6 | 237 278 137 |
| 125 123579 17 | 8 1237 127 | 4 6 13579 |
| 1258 123579 6 | 127 1237 4 | 2379 278 13579 |
|-------------------------+-------------------------+-------------------------|
| 6 12 8 | 3 4 129 | 5 27 #79 |
| 7 4 9 | 6 5 28 | 238 1 38 |
| 125 125 3 | 127 127 89 |#89 4 6 |
*-----------------------------------------------------------------------------*
| Help! I see this xy-chain but can't see the pseudo-cell 78 or the chain to remove 7's from r12c9. |
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storm_norm
Joined: 18 Oct 2007 Posts: 1741
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Posted: Sun May 10, 2009 10:08 pm Post subject: |
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dan,
Code: | .------------------------.------------------------.------------------------.
| 9 6 2 | 47 78 5 | 1 3 478 |
| 3 8 5 | 1247 1267 127 |*67 9 47 |
| 4 17 17 | 9 68 3 |*68 5 2 |
:------------------------+------------------------+------------------------:
| 128 1237 4 | 5 9 6 | 237 278 137 |
| 125 123579 17 | 8 1237 127 | 4 6 13579 |
| 1258 123579 6 | 127 1237 4 | 2379 278 13579 |
:------------------------+------------------------+------------------------:
| 6 12 8 | 3 4 129 | 5 27 *79 |
| 7 4 9 | 6 5 28 | 238 1 38 |
| 125 125 3 | 127 127 89 |*89 4 6 |
'------------------------'------------------------'------------------------' |
r23c7 is the pseudocell {7,8} both containing 6 also
(7=9)r7c9 - (9=8)r9c7 - {(8=6)r3c7 - (6=7)r2c7} <--- brackets is the pseudocell.
79-98-87 |
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arkietech
Joined: 31 Jul 2008 Posts: 1834 Location: Northwest Arkansas USA
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Posted: Sun May 10, 2009 11:00 pm Post subject: |
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storm_norm wrote: | r23c7 is the pseudocell {7,8} both containing 6 also
(7=9)r7c9 - (9=8)r9c7 - {(8=6)r3c7 - (6=7)r2c7} <--- brackets is the pseudocell.
79-98-87 |
Thanks,
I finally see it! I keep trying to go two ways on an xy-wing when you just have to go one. ie r9c7<>7 causing r2c7 to be 7 |
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storm_norm
Joined: 18 Oct 2007 Posts: 1741
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Posted: Sun May 10, 2009 11:46 pm Post subject: |
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arkietech wrote: | storm_norm wrote: | r23c7 is the pseudocell {7,8} both containing 6 also
(7=9)r7c9 - (9=8)r9c7 - {(8=6)r3c7 - (6=7)r2c7} <--- brackets is the pseudocell.
79-98-87 |
Thanks,
I finally see it! I keep trying to go two ways on an xy-wing when you just have to go one. ie r9c7<>7 causing r2c7 to be 7 |
that chain is valid in both directions.
r2c7 <> 7 leads to r7c9 = 7 |
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Marty R.
Joined: 12 Feb 2006 Posts: 5770 Location: Rochester, NY, USA
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Posted: Tue May 12, 2009 3:13 pm Post subject: |
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Same as Dan's two-stepper, UR 47 and XY 798. |
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