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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Wed Mar 23, 2011 4:47 pm Post subject: Puzzle 11/03/23: ~ Difficult+ |
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| Code: | +-----------------------+
| 4 . . | 1 9 3 | 7 2 . |
| . 1 . | 7 2 . | 4 . . |
| . . 3 | . . . | . 1 . |
|-------+-------+-------|
| 3 2 . | 9 . . | 5 . . |
| 6 9 . | . 7 . | 3 . 1 |
| 7 . . | . . 1 | . . . |
|-------+-------+-------|
| 1 3 . | 2 5 . | 9 . 7 |
| 9 . 2 | . . . | . 5 . |
| . . . | . 6 . | 1 . . |
+-----------------------+
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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: Wed Mar 23, 2011 10:04 pm Post subject: |
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Fascinating puzzle for me! I spent a lot of time looking at DPs around 348 etc and then the UR(48) in b7/b8. Considering the streams from that UR, this Kraken emerged...
| Code: | kraken-col(3) c4 ; r89c4<>8
(3)r8c4 - r8c9=(3-5)r2c9=r2c1 - (5=8)r9c1
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(3)r9c4 - r9c8=(3-6)r2c8=r7c8 - (6=8)r8c7 |
Given that there are only two streams it feels like there should be a chain that does this? Like...
| Code: | | (8=5)r9c1 - r2c1=(5-3)r2c9=r8c9 - r8c4=r9c4 - r9c8=(3-6)r2c8=r7c8 - (6=8)r8c7 |
I can't see why that would make the two eliminations of (8)r89c4? |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Thu Mar 24, 2011 12:28 am Post subject: |
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How about this perspective of your chain?
| Code: | (8=5)r9c1 - r2c1=(5-3)r2c9=r8c9 - r8c4=r9c4 - r9c8=(3-6)r2c8=r7c8 - (6=8)r8c7 => r8c2,r9c8<>8
(8=5)r9c1 - r2c1=(5-3)r2c9=r8c9 - r8c4=r9c4(3) => r9c4<>8
(3)r8c4=r9c4 - r9c8=(3-6)r2c8=r7c8 - (6=8)r8c7 => r8c4<>8
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Thu Mar 24, 2011 8:27 am Post subject: |
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| Thanks Danny. That's clear - wonder how one might annotate just the single chain to make the eliminations clear to a reader. I tried placing pauses/asterisks but without something to match them up it didn't look very helpful! |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Thu Mar 24, 2011 4:17 pm Post subject: |
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| peterj wrote: | | That's clear - wonder how one might annotate just the single chain to make the eliminations clear to a reader. I tried placing pauses/asterisks but without something to match them up it didn't look very helpful! |
Peter, I don't recall any notational standard for marking chains with intermediate eliminations. There was a discussion a short while back between RonK and David P. Bird in another forum on how to track all of the eliminations associated with a chain. It's not that difficult, but I managed to forgotten the details.
As for your chain, I'd condense my previous notation to:
| Code: | | ----------------------------------- | => r8c4<>8
(8=5)r9c1 - r2c1=(5-3)r2c9=r8c9 - r8c4=r9c4 - r9c8=(3-6)r2c8=r7c8 - (6=8)r8c7 => r8c2,r9c8<>8
| ------------------------------ | => r9c4<>8
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FWIW: I just let my solver find the three chains as if they were independent. Besides, the longer chain can often be shortened when it's independent of the other two chains.
| Code: | (8)r8c7 = r3c7 - r1c9 = r1c23 - r2c1 = (8)r9c1 => r8c2,r9c8<>8
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