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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Wed Apr 29, 2009 3:42 pm Post subject: Set XY_02 Puzzle 102 |
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| Code: | +-----------------------+
| 3 . . | . . 9 | 7 1 2 |
| . 2 . | . . . | . 9 . |
| . . 5 | . . 7 | . . . |
|-------+-------+-------|
| . . . | . . . | 2 5 . |
| . . . | . . . | . . . |
| 2 . 1 | . . 5 | 9 6 . |
|-------+-------+-------|
| 1 . . | 9 . 8 | 6 . . |
| 5 6 . | 1 . 2 | . 7 4 |
| 7 . . | . . . | . 2 . |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Wed Apr 29, 2009 9:03 pm Post subject: |
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notice the x-wing overlay on candidate 5 in the UR {56} cells in r19c45
any other 6's in row 1 or 9 destroy the UR. in this care there are two. one is in row 1 at A and one is row 9 at B
UR56[(6)A = (6)B]...
| Code: | .------------------.------------------.------------------.
| 3 8 A46 |U456 U456 9 | 7 1 2 |
| 46 2 7 | 3468 1 346 | 5 9 368 |
| 9 1 5 | 368 2 7 | 34 48 368 |
:------------------+------------------+------------------:
| 48 9 D34 | 7 68 C36 | 2 5 1 |
| 68 5 E3-6 | 2 9 1 | 34 48 7 |
| 2 7 1 | 34 48 5 | 9 6 38 |
:------------------+------------------+------------------:
| 1 4 2 | 9 7 8 | 6 3 5 |
| 5 6 9 | 1 3 2 | 8 7 4 |
| 7 3 8 |U456 U456 B46 | 1 2 9 |
'------------------'------------------'------------------' |
UR56[(6)A = (6)B] - (6=3)C - (3)D = (3)E; E is not 6
for a one stepper. |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Wed Apr 29, 2009 10:06 pm Post subject: |
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| storm_norm wrote: | UR56[(6)A = (6)B] - (6=3)C - (3)D = (3)E; E is not 6
for a one stepper. |
Brilliant Norm!  It took me an xy-wing 346, er on 3 then an xy-chain --
ugly compared to yours. |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Thu Apr 30, 2009 2:43 am Post subject: |
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Great observation Norm. After basics, I did not even see the potential UR.
I used a xy-wing 346 with pivot 36 at r4c6 and transported the pincer at r4c3 to r2c1 to delete 4 at r2c6,
and then I spotted the Type 2 UR 56 in r19c45 that Norm utilized to complete the puzzle in two steps.
Ted |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Thu Apr 30, 2009 3:53 am Post subject: |
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Norm: Impressive and interesting.
I'm also interested in URs from the viewpoint of an outside condition forcing a UR to occur. You provided a great dual.
| Code: | *-----------------------------------------------------------*
| 3 8 A46 | 456 456 9 | 7 1 2 |
| 46 2 7 | 3468 1 346 | 5 9 368 |
| 9 1 5 | 368 2 7 | 34 48 368 |
|-------------------+-------------------+-------------------|
| 48 9 D34 | 7 68 C36 | 2 5 1 |
| 68 5 36 | 2 9 1 | 34 48 7 |
| 2 7 1 | 34 48 5 | 9 6 38 |
|-------------------+-------------------+-------------------|
| 1 4 2 | 9 7 8 | 6 3 5 |
| 5 6 9 | 1 3 2 | 8 7 4 |
| 7 3 8 | 456 456 B46 | 1 2 9 |
*-----------------------------------------------------------*
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| Code: | (6=4)A - (4=3)D - (3=6)C - (6=4)B
Left-to-Right: A=4 D=3 C=6 B=4 => <56> UR in [r19c45] contradiction!
Right-to-Left: B=6 C=3 D=4 A=6 => <45> UR in [r19c45] contradiction!
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Thus, we can conclude that A<>4 and B<>6 . |
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