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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Tue Mar 30, 2010 3:33 pm Post subject: Puzzle 10/03/30 (D) |
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| Code: | +-----------------------+
| . . 6 | 2 . . | 8 . . |
| . . . | 7 9 . | . . . |
| 9 . . | . . . | . 2 . |
|-------+-------+-------|
| 8 3 . | 5 . . | . . 9 |
| . 2 . | . . . | . 8 . |
| . . . | . . 2 | . 3 7 |
|-------+-------+-------|
| 4 . . | . . . | 6 7 . |
| . . 3 | . 1 8 | 9 . . |
| . . . | 3 . 6 | . . . |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site |
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Tue Mar 30, 2010 5:21 pm Post subject: |
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I tried hard to only use uniqueness ... but needed an XY-wing
Only the first two URs are actually needed when I went back to look at it!
| Quote: | Type 1 UR (14); r2c9<>1,4
Type 4 UR (68); r6c45<>6
Type 4 UR (18); r2c34<>1
Hidden UR (59) r9c2; r6c3<>5
Hidden UR (25) r9c1; r2c3<>5
xy-wing (146) r4c5; r5c1<>1
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Tue Mar 30, 2010 8:45 pm Post subject: |
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I struggled to find a one stepper....it is not pretty. | Code: | *--------------------------------------------------------------------*
| 3 7 6 | 2 5 14 | 8 9 14 |
| 125 1458 12458 | 7 9 14 | 3 146 1456 |
| 9 145 145 | 68 68 3 | 7 2 145 |
|----------------------+----------------------+----------------------|
| 8 3 14 | 5 46 7 | 2 16 9 |
| 156 2 7 | 16 3 9 | 145 8 146 |
| 156 1459 1459 | 168 468 2 | 15 3 7 |
|----------------------+----------------------+----------------------|
| 4 18 18 | 9 2 5 | 6 7 3 |
| 7 6 3 | 4 1 8 | 9 5 2 |
| 25 59 259 | 3 7 6 | 14 14 8 |
*--------------------------------------------------------------------*
(6=4)r4c5-(4=1)r4c3-r56c1=r2c1-(1=6)[ALS:r2c68]-r2c9=(6)r5c9; r4c8,r5c4<>6
stte
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Tue Mar 30, 2010 11:53 pm Post subject: |
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Two steps.
| Quote: | Look at the outside implications to prevent the deadly pattern for the potential UR68 in r36c45.
Digit 6: the only outside 6 in r36 is r6c1,
Digit 8: an x-wing overlay exists so no implications exist.
Thus, to prevent the deadly pattern, r6c1=6,
xy-wing -146 with vertex in r4c5 completes the puzzle.
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Ted |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Wed Mar 31, 2010 12:03 am Post subject: |
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| arkietech wrote: | I struggled to find a one stepper....it is not pretty. | Code: | *--------------------------------------------------------------------*
| 3 7 6 | 2 5 14 | 8 9 14 |
| 125 1458 12458 | 7 9 14 | 3 146 1456 |
| 9 145 145 | 68 68 3 | 7 2 145 |
|----------------------+----------------------+----------------------|
| 8 3 14 | 5 46 7 | 2 16 9 |
| 156 2 7 | 16 3 9 | 145 8 146 |
| 156 1459 1459 | 168 468 2 | 15 3 7 |
|----------------------+----------------------+----------------------|
| 4 18 18 | 9 2 5 | 6 7 3 |
| 7 6 3 | 4 1 8 | 9 5 2 |
| 25 59 259 | 3 7 6 | 14 14 8 |
*--------------------------------------------------------------------*
(6=4)r4c5-(4=1)r4c3-r56c1=r2c1-(1=6)[ALS:r2c68]-r2c9=(6)r5c9; r4c8,r5c4<>6
stte
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Dan,
I think your chain is very pretty. It is long, but that is what was needed to do the thing and to me long is just long; it is not ugly. Besides, your use of the ALS was a special touch.
Cool move.
Ted |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Apr 01, 2010 10:13 pm Post subject: |
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Same as Ted, a Type 4 UR (68) and XY-Wing (461), except I played a W-Wing (15) in between.
The UR can also be viewed as containing a 14 pseudo cell to form a 1459 quad. |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Thu Apr 01, 2010 10:49 pm Post subject: |
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| Marty R. wrote: | Same as Ted, a Type 4 UR (6 and XY-Wing (461), except I played a W-Wing (15) in between.
The UR can also be viewed as containing a 14 pseudo cell to form a 1459 quad. |
Marty,
The quad formed by using the pseudocell 14 of the UR results in setting r6c1=1, which is the exact result of my analysis of the outside implications of the UR. Very interesting........
Ted |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Apr 01, 2010 11:43 pm Post subject: |
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| Yes, the analysis you did, playing it with a pseudo cell and playing it as an ordinary Type 4 all produced the same result. |
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