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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Wed Jun 10, 2009 7:57 pm Post subject: Set XY_03 Puzzle 015 |
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Probably easy for an XY_nn puzzle.
| Code: | +-----------------------+
| 9 . . | . . 5 | 6 . 8 |
| . 5 . | . . 2 | 1 . . |
| . . . | 8 1 . | . . . |
|-------+-------+-------|
| . . 5 | 7 . 8 | 9 . . |
| . . 9 | . 5 . | 2 . . |
| 3 6 . | 2 . 1 | 8 . . |
|-------+-------+-------|
| 5 9 . | 6 2 7 | 4 . . |
| . . . | . . . | . . . |
| 6 . . | . . . | . . 1 |
+-----------------------+
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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: Thu Jun 11, 2009 6:56 am Post subject: |
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this grid is after the xy-wing {3,4,6} that very nicely removes the 3's from r89c5, in the UR pattern on {4,8} in r89c35... notice the xy-wing that is formed from the extra candidates?
| Code: | .---------------.---------------.---------------.
| 9 1 34 | 34 7 5 | 6 2 8 |
| 8 5 36 | 9 36 2 | 1 47 47 |
| 24 7 246 | 8 1 46 | 3 5 9 |
:---------------+---------------+---------------:
| 124 {24} 5 | 7 36 8 | 9 13 46 |
| 17 8 9 | 34 5 46 | 2 13 67 |
| 3 6 {47} | 2 9 1 | 8 47 5 |
:---------------+---------------+---------------:
| 5 9 1 | 6 2 7 | 4 8 3 |
| 47 3 {7}48 | 1 48 9 | 5 6 2 |
| 6 -24 {2}48 | 5 48 3 | 7 9 1 |
'---------------'---------------'---------------' |
with the help of the UR{4,8}, the xy-wing {2,4,7} is formed and eliminates the 2 in r9c2 to solve it.
or...
UR48[(2)r9c3 = (7)r8c3] - (7=4)r6c3 - (4=2)r4c2; r9c2 <> 2 |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Thu Jun 11, 2009 1:05 pm Post subject: |
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My first step was an extended xyz-wing 346 in r4c5 to delete 3 in r5c6. The extension is: If r4c5=6 then r2c5=3 so r89c5<>3 and r9c6=3 which means r5c6<>3. Or, as a chain: (6)r4c5 - (6=3)r2c5 - (3)r89c5 = (3)r9c6; r5c6<>3. This step resulted in identical code as posted by Norm after his initial xy-wing 346.
Then I noticed the UR48 (also described by Norm) which provided the subset 27 to form the xy-wing 247 with pivot 27 in r89c3 that deleted the 4 in r4c2.
Ted |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Thu Jun 11, 2009 1:21 pm Post subject: |
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Nice find Norm. 
two w-wings will solve it also:
w-wing 34
w-wing 42 |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Jun 15, 2009 3:45 pm Post subject: |
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| I started with a W-Wing on 34. Then the UR on 48 worked out just like a little Mixed W-Wing. In the grid shown, if r8c3 = 7 then r3c1 = 2 and the 2 is eliminated from r3c3. |
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