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Clement
Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania
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 Posted: Sun Mar 28, 2010 11:36 pm Post subject: March 29 VH |
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Four steps!
1) UR 89 eliminating 9 in r24c8
2) X-Wing in 9 r15c58 eliminating 9 in r5c4
3) X-Wing in 9 r24c49 eliminating 9's in r4c31
4) XY-Wing 46 49 69 eliminating 6's in r1c13 solving the puzzle. |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Sun Mar 28, 2010 11:58 pm Post subject: |
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There is a single step:
XY wing <469>
r2c34 and r1c5 which takes out the 6 in r1c1. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Mar 29, 2010 1:27 am Post subject: |
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| I did not actually finish the puzzle, but I saw three moves which I thought might each finish it off. They were M-Wing (46), XY-Chain based on a UR (89) and XY-Wing (496). |
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Mon Mar 29, 2010 4:32 pm Post subject: |
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For those who don't like searching for xy/w/m-wings I found a path using mostly uniqueness....
Type-4 UR (89); r2c8<>9, r4c8<>9
Hidden Rectangle (26) apex at r3c8; r1c3<>6
x-wing (9); r5c4<>9
BUG+2 Either r3c3 or r1c8 = 6; r3c8<>6
Singles...
Multi-value Wings avoided... |
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Clement
Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania
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| Posted: Mon Mar 29, 2010 5:57 pm Post subject: March 29 VH |
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Yes, Mogulmeister & Marty,
XY-Wing (469) is a single steper. I missed some basic eliminations. |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Mon Mar 29, 2010 6:07 pm Post subject: |
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..but that is what makes this game fun..some puzzles are made even more enjoyable as we go through our private arsenal of techniques and arrive at a solution.
An efficient single shot takedown isn't always nirvana. As in life, the journey is often better than the arriving. |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Mon Mar 29, 2010 11:45 pm Post subject: |
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A couple of posts used the UR89 with the x-wing 8 overlay to eliminate 9 in r24c8.
However if we look at the implications inside the UR, we see another possibility. To prevent the deadly pattern, either r2c8=6 or r4c8=7. So, looking at these implications we get:
If r2c8=6, then r2c3=4, then r2c4=9.
If r4c8=7, then r5c8=9;
Thus r5c4<>9 so we have an additional deletion. Sorry to say, in the case that the additional deletion is not very helpful.
Ted |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Tue Mar 30, 2010 12:01 am Post subject: |
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| tlanglet wrote: | A couple of posts used the UR89 with the x-wing 8 overlay to eliminate 9 in r24c8.
However if we look at the implications inside the UR, we see another possibility. To prevent the deadly pattern, either r2c8=6 or r4c8=7. So, looking at these implications we get:
If r2c8=6, then r2c3=4, then r2c4=9.
If r4c8=7, then r5c8=9;
Thus r5c4<>9 so we have an additional deletion. Sorry to say, in the case that the additional deletion is not very helpful.
Ted |
Ted,
I don't know if you saw my post about using the 89 UR as a basis for an XY-Chain. This was my grid after basics.
| Code: |
+-----------+----------+----------+
| 67 37 236 | 8 69 5 | 1 269 4 |
| 1 5 46 | 49 7 2 | 3 689 89 |
| 8 9 246 | 1 46 3 | 5 26 7 |
+-----------+----------+----------+
| 67 2 36 | 39 5 1 | 4 789 89 |
| 5 37 8 | 349 49 6 | 2 79 1 |
| 9 4 1 | 2 8 7 | 6 3 5 |
+-----------+----------+----------+
| 3 1 5 | 7 2 9 | 8 4 6 |
| 2 8 9 | 6 1 4 | 7 5 3 |
| 4 6 7 | 5 3 8 | 9 1 2 |
+-----------+----------+----------+
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Play this puzzle online at the Daily Sudoku site
The DP killers have to be 6 in r2c8 or 7 in r4c8. If r2c8=6, then r1c1=7. Either way, r4c1<>7 and that's all that's needed. |
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