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Trivial but interesting in sat 23rd VH

 
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George Woods



Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK

PostPosted: Tue Jun 26, 2007 12:41 pm    Post subject: Trivial but interesting in sat 23rd VH Reply with quote

On this one I found a logic that I have not encountered before. This was at the stage just before the xwings and xy wing : Analyzing box3 we see that 4 is either in cell 1 or 2 by analyzing the row or in cell 2 or8 by analyzng the column. The only cell satisfying both is cell 2 which must be 4. Is this a common move?, 'cos I don't think I have met it before!
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Tue Jun 26, 2007 3:38 pm    Post subject: Reply with quote

Could you stick up the grid ?
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jLo



Joined: 30 Apr 2007
Posts: 55

PostPosted: Tue Jun 26, 2007 4:11 pm    Post subject: Reply with quote

Quote:

On this one I found a logic that I have not encountered before. This was at the stage just before the xwings and xy wing : Analyzing box3 we see that 4 is either in cell 1 or 2 by analyzing the row or in cell 2 or8 by analyzng the column. The only cell satisfying both is cell 2 which must be 4. Is this a common move?, 'cos I don't think I have met it before!


Code:

+--------------+-------------+--------------+
|      26      |             | 246 246      |
|         124  |        24   | 124          |
| 124     1246 | 24          |     1246     |
+--------------+-------------+--------------+
|         56   |    15       |     16       |
| 23      2356 | 24 259 246  |          49  |
|      26      |    129 1246 | 146      149 |
+--------------+-------------+--------------+
|              |        12   | 124      14  |
| 12      12   |             |              |
| 1234    1234 |    12       |     124      |
+--------------+-------------+--------------+


I think this is just simple row/column lockout.

4 in row 1 must be in Box 3, eliminating 4 from R3c8 (and R2C7)
4 in Box 7 must be in Row 9, eliminating 4 from R9C8

That leaves a single 4 in column 8 - R1C8=4
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George Woods



Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK

PostPosted: Tue Jun 26, 2007 10:08 pm    Post subject: row/column lockout. Reply with quote

thanks :- As I said I do not remeber having met it before andso did not have a convenient description but " row/column lockout." seems to do the job!
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Marty R.



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

PostPosted: Wed Jun 27, 2007 12:37 am    Post subject: Reply with quote

That's a new term to me, "row/column lockout." It's more commonly known as "locked candidates" or "box-line reduction."
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