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Bud
Joined: 06 May 2010
Posts: 47
Location: Tampa, Florida
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 Posted: Thu Oct 14, 2010 3:41 pm Post subject: AHS-ALS Logic Example |
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I learned AHS=ALS logic from Allan Barker. This is an excellent example of one of these techniques. The (16)AHS cells are labeled B and the (125) ALS cells are labeled A in the puzzle grid. Each of these is contolled by a single digit ! in the cell labeled C. If C<>1 the AHS becomes a locked set 16 and if C=1 the ALS becomes a locked set 25. In either case 5 cannot be in r4c4.
AHS-ALS Logic Example | Code: |
+------------------+-------------------+----------------+
| 2578 359 23578 | 12359 6 12359 | 1279 4 1379 |
| 27 39 4 | 8 39 12A | 127 6 5 |
| 256 1 2356 | 23459 7 23459 | 29 8 39 |
+------------------+-------------------+----------------+
| 4 35 1356B | 13-569B 359 13579C| 789 2 789 |
| 56 7 9 | 256 8 25A | 3 1 4 |
| 18 2 138 | 13 4 79 | 579 59 6 |
+------------------+-------------------+----------------+
| 159 6 15 | 34 2 34 | 1589 7 189 |
| 3 8 12 | 7 59 6 | 4 59 12 |
| 2579 4 257 | 59 1 8 | 6 3 29 |
+------------------+-------------------+----------------+ |
The original puzzle is the 9-26-10 tough at sudoku.com.au. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Thu Oct 14, 2010 5:18 pm Post subject: |
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Nice find! An alternate perspective similar to what's done in this forum:
| Code: | ALS(5=21)r52c6 - AHS(1=16)r4c634 => r4c4<>5
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[Edit: several attempts to properly present information.]
Last edited by daj95376 on Thu Oct 14, 2010 9:54 pm; edited 3 times in total |
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ronk
Joined: 07 May 2006
Posts: 398
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| Posted: Thu Oct 14, 2010 7:56 pm Post subject: |
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| daj95376 wrote: | Nice find! An alternate perspective similar to what's done in this forum:
| Code: | A A CBB
(5=2)r5c6 - (2=1)r2c6 - (1=16)r4c634 => r4c4<>5
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I don't actually recall seeing almost-hidden-sets in an AIC on this forum. In any case, it would be clearer if the set were identified as hidden, for example ...
(5=2)r5c6 - (2=1)r2c6 - (1)r4c6 = (hp16)r4c34 => r4c4<>5 |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Thu Oct 14, 2010 8:30 pm Post subject: |
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| ronk wrote: | (5=2)r5c6 - (2=1)r2c6 - (1)r4c6 = (hp16)r4c34 => r4c4<>5
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Considering the fact that I didn't properly identify the ALS as (5=21)r52c6, then partitioning the AHS term seems appropriate.
I prefer your notation because it shows that "almost" isn't needed. It's simply an AIC with a hidden pair term. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Sat Oct 16, 2010 9:04 am Post subject: |
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| Quote: | | I don't actually recall seeing almost-hidden-sets in an AIC on this forum |
might want to look a little closer. I and several others have posted AHS in AIC's in this forum. |
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ronk
Joined: 07 May 2006
Posts: 398
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| Posted: Sat Oct 16, 2010 9:33 am Post subject: |
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| storm_norm wrote: | | Quote: | | I don't actually recall seeing almost-hidden-sets in an AIC on this forum |
might want to look a little closer. I and several others have posted AHS in AIC's in this forum. |
Thanks for the links. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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