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mm 1309, 2/8/09 Diabolical

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storm_norm

Joined: 18 Oct 2007
Posts: 1741

Posted: Mon Feb 09, 2009 2:24 am Post subject: mm 1309, 2/8/09 Diabolical

Code:

+-------+-------+-------+
| . 9 5 | . . . | 4 1 . |
| . . 1 | . . . | . 7 9 |
| . . . | . 5 . | . . . |
+-------+-------+-------+
| . . . | 3 . 2 | . 4 . |
| 6 . . | . 8 . | . . 5 |
| . 2 . | 1 . 5 | 3 . . |
+-------+-------+-------+
| . . . | . 9 . | . . . |
| 8 3 . | . . . | 2 . . |
| . 4 7 | . . . | . 6 . |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Mon Feb 09, 2009 3:12 am Post subject:

One-Trick Pony.

Lots of Extraneous Steps wrote:

gM-Wing: (5=9)r8c8 - (9)r9c7 = (9-5)r9c1 = (5)r9c4 => [r8c4]<>5

Last edited by daj95376 on Mon Feb 16, 2009 1:55 am; edited 1 time in total

storm_norm

Joined: 18 Oct 2007
Posts: 1741

Posted: Mon Feb 09, 2009 3:21 am Post subject:

Quote:

Lots of Extraneous Steps wrote

ROFL

funny.

Marty R.

Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

Posted: Sun Feb 15, 2009 5:21 pm Post subject:

Quote:

M-Wing: (5=9)r8c8 - (9)r9c7 = (9-5)r9c1 = (5)r9c4 => [r8c4]<>5

Danny,

Here's my position after basics. How do you get rid of the 1 in r9c1 to do the M-Wing?

Code:

+---------------+---------------+---------------+
| 23 9 5 | 678 23 678 | 4 1 68 |
| 23 68 1 | 268 234 3468 | 5 7 9 |
| 47 678 468 | 9 5 1 | 68 3 2 |
+---------------+---------------+---------------+
| 1579 1578 89 | 3 67 2 | 16789 4 1678 |
| 6 17 3 | 4 8 9 | 17 2 5 |
| 479 2 489 | 1 67 5 | 3 89 678 |
+---------------+---------------+---------------+
| 15 156 2 | 5678 9 34 | 178 58 34 |
| 8 3 69 | 567 14 467 | 2 59 147 |
| 159 4 7 | 258 123 38 | 189 6 138 |
+---------------+---------------+---------------+

Play this puzzle online at the Daily Sudoku site[/quote]

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Sun Feb 15, 2009 7:15 pm Post subject:

Marty R. wrote:

Quote:

M-Wing: (5=9)r8c8 - (9)r9c7 = (9-5)r9c1 = (5)r9c4 => [r8c4]<>5

Here's my position after basics. How do you get rid of the 1 in r9c1 to do the M-Wing?

Here's my gM-Wing from another perspective -- a forcing chain. The <1> in [r9c1] never figures into the logic.

Code:

[r8c8]= 5 => [r8c4]<>5

[r8c8]<>5 [r8c8]=9 [r9c7]<>9 [r9c1]=9 [r9c1]<>5 [r9c4]=5 => [r8c4]<>5

Last edited by daj95376 on Mon Feb 16, 2009 1:56 am; edited 1 time in total

Marty R.

Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

Posted: Sun Feb 15, 2009 10:27 pm Post subject:

OK, fair enough. But may I ask where the M-Wing terminology comes into play?

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Mon Feb 16, 2009 2:01 am Post subject:

Marty R. wrote:

OK, fair enough. But may I ask where the M-Wing terminology comes into play?

Ahhhhh

I've been working with gM-Wing for so long that I didn't catch my mistake in calling it an M-Wing.

In the generalized case, cell [r9c1] only needs to contain <59> ... and does not have to be a bivalue cell.

See Keith's reference to Nataraj and Asellus in this link.

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