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Free Press Jul 30, 2010

 
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
PostPosted: Sat Jul 31, 2010 3:13 pm    Post subject: Free Press Jul 30, 2010 Reply with quote
I have not yet tried this, but my solver suggests it is in the "don't bother" category.
Code:
Puzzle: FP073010
+-------+-------+-------+
| . . . | . 6 . | 8 . . |
| . 7 . | 5 . . | . 2 . |
| 5 . 6 | 8 . . | . . 9 |
+-------+-------+-------+
| . . 1 | . . 5 | . 8 . |
| . . 3 | . . . | 9 . . |
| . . . | 6 2 . | 3 . . |
+-------+-------+-------+
| 6 . . | . . 7 | 1 . 2 |
| . 3 . | . . 6 | . 7 . |
| . . 5 | . 1 . | . . . |
+-------+-------+-------+
Keith
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Sat Jul 31, 2010 5:04 pm    Post subject: Re: Free Press Jul 30, 2010 Reply with quote
keith wrote:
I have not yet tried this, but my solver suggests it is in the "don't bother" category.

My solver says: be prepared to use 3x grouped strong links!
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
PostPosted: Sat Jul 31, 2010 6:39 pm    Post subject: Reply with quote
After basics:
Code:
+-------------------+-------------------+-------------------+
| 2349  1249  249   | 7     6     12349 | 8     1345  1345  |
| 3489  7     489   | 5     349   1349  | 46    2     1346  |
| 5     124   6     | 8     34    1234  | 7     134   9     |
+-------------------+-------------------+-------------------+
| 49    469   1     | 349   3479  5     | 2     8     467   |
| 248   24568 3     | 1     478   48    | 9     456   4567  |
| 489   4589  7     | 6     2     489   | 3     145   145   |
+-------------------+-------------------+-------------------+
| 6     489   489   | 349   5     7     | 1     349   2     |
| 1     3     249   | 249   489   6     | 5     7     48    |
| 7     249   5     | 2349  1     3489  | 46    3469  3468  |
+-------------------+-------------------+-------------------+

Here's what Sudoku Susser says:

2 x Nishio
13 x Comprehensive Forcing Chains
1 x Simple Forcing Chains
1 x Unique Rectangles and Loops

Nishio is a fancy word for guessing. Comprehensive chains are generally not something that humans would recognize.

Danny, if you think there is some way a human might make much progress, I'd like to hear it.

Keith
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Sat Jul 31, 2010 7:19 pm    Post subject: Reply with quote
Here is the shortest chain that my solver found that cracks this puzzle in one step. All of the other chains that crack the puzzle also use the 3x grouped strong links on <3> as well.

(8)r8c5 = (8-7)r5c5 = (7-3)r4c5 = r23c5 - r123c6 = (3)r9c6 => r9c6<>8

Nothing less complex made any headway.

Regards, Danny

Last edited by daj95376 on Sat Jul 31, 2010 10:01 pm; edited 1 time in total
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ronk



Joined: 07 May 2006
Posts: 398
PostPosted: Sat Jul 31, 2010 7:26 pm    Post subject: Reply with quote
One stepper, an ALS-xz involving 7 cells.
Quote:

ALS-xz: sets A={r4c4,r5c6,r6c6}={3489}, B={r7c4,r8c4,r9c4,r8c5}={23489}, x=3, z=8 => r5c5,r9c6<>8

[edit; Deleted a superfluous opening step.]
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Mogulmeister



Joined: 03 May 2007
Posts: 1151
PostPosted: Sun Aug 01, 2010 11:57 am    Post subject: Reply with quote
keith wrote:


Nishio is a fancy word for guessing.


Japanese.
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