Help on black belt puzzle please

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Help on black belt puzzle please

Postby mayres » Fri Mar 28, 2008 3:36 am

I thought this was going to be fairly easy at first but for some reason I have found myself stumped. If someone could please tell me a move at this position I would be most apprecitve - remember you are talking to someone who is not an expert so please give some details to the logic if possible. THANKS! Here is the start
Code: Select all
  *--------------------------------*
 |    7     |       5  |          |
 |       4  |    1     |          |
 | 6        |    7     | 5     9  |
 |----------+----------+----------|
 |          |       3  | 8     7  |
 | 9     3  |          | 2     1  |
 | 7     1  | 6        |          |
 |----------+----------+----------|
 | 1     2  |    9     |       4  |
 |          |    5     | 1        |
 |          | 7        |    2     |
 *--------------------------------*

And here is where I am stuck
Code: Select all
  *--------------------------------------------------------------------*
 | 23     7      9      | 348    36     5      | 346    1      238    |
 | 235    235    4      | 9      1      68     | 367    378    238    |
 | 6      1      8      | 234    7      24     | 5      34     9      |
 |----------------------+----------------------+----------------------|
 | 245    2456   56     | 1      24     3      | 8      9      7      |
 | 9      48     3      | 5      48     7      | 2      6      1      |
 | 7      28     1      | 6      28     9      | 34     345    35     |
 |----------------------+----------------------+----------------------|
 | 1      356    2      | 38     9      68     | 37     357    4      |
 | 38     9      7      | 24     5      24     | 1      38     6      |
 | 3458   3456   56     | 7      36     1      | 9      2      358    |
 *--------------------------------------------------------------------*
mayres
 
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Postby Draco » Fri Mar 28, 2008 4:46 am

Chain r8c1-3-r7c2=3=r2c2 and r8c1-8-r8c8=8=r2c8, ergo r2c8<>3. Then XY-Wing from r8c8, SSTS
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Postby daj95376 » Fri Mar 28, 2008 4:58 am

You have a Unique Rectangle Type 1 present for candidates 24 in r38c46. This leaves [r3c4]=3 and the puzzle cracks.

Code: Select all
+--------------------------------------------------------------------+
|  23     7      9     |  348    36     5     |  346    1      238   |
|  235    235    4     |  9      1      68    |  367    378    238   |
|  6      1      8     | *3-24   7     *24    |  5      34     9     |
|----------------------+----------------------+----------------------|
|  245    2456   56    |  1      24     3     |  8      9      7     |
|  9      48     3     |  5      48     7     |  2      6      1     |
|  7      28     1     |  6      28     9     |  34     345    35    |
|----------------------+----------------------+----------------------|
|  1      356    2     |  38     9      68    |  37     357    4     |
|  38     9      7     | *24     5     *24    |  1      38     6     |
|  3458   3456   56    |  7      36     1     |  9      2      358   |
+--------------------------------------------------------------------+
daj95376
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Posts: 2624
Joined: 15 May 2006

Postby wintder » Fri Mar 28, 2008 5:27 am

There is also a longer way, geez, at least one?

You could use an ER to eliminate the 3 in row 2 column 8.

Code: Select all
.------------------.------------------.------------------.
| 23*   7     9    | 348   36    5    | 346   1     238  |
| 235*  235*  4    | 9     1     68   | 367   78-3  238  |
| 6     1     8    | 234   7     24   | 5     34    9    |
:------------------+------------------+------------------:
| 245   2456  56   | 1     24    3    | 8     9     7    |
| 9     48    3    | 5     48    7    | 2     6     1    |
| 7     28    1    | 6     28    9    | 34    345   35   |
:------------------+------------------+------------------:
| 1     356   2    | 38    9     68   | 37    357   4    |
| 38#   9     7    | 24    5     24   | 1     38#   6    |
| 3458  3456  56   | 7     36    1    | 9     2     358  |
'------------------'------------------'------------------'



Then you could use an xy wing to make it easy.

Code: Select all
.------------------.------------------.------------------.
| 23    7     9    | 348   36    5    | 346   1     238  |
| 235   235   4    | 9     1     68   | 36-7  78*   238  |
| 6     1     8    | 234   7     24   | 5     34    9    |
:------------------+------------------+------------------:
| 245   2456  56   | 1     24    3    | 8     9     7    |
| 9     48    3    | 5     48    7    | 2     6     1    |
| 7     28    1    | 6     28    9    | 34    345   35   |
:------------------+------------------+------------------:
| 1     356   2    | 38    9     68   | 37*   357   4    |
| 38    9     7    | 24    5     24   | 1     38*   6    |
| 3458  3456  56   | 7     36    1    | 9     2     358  |
'------------------'------------------'------------------'
wintder
 
Posts: 297
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Re: Help on black belt puzzle please

Postby Cec » Fri Mar 28, 2008 10:00 am

mayres wrote:"...If someone could please tell me a move at this position I would be most appreciative - remember you are talking to someone who is not an expert so please give some details to the logic if possible..."
Code: Select all
 *--------------------------------------------------------------------*
 | 23     7      9      | 348    36     5      | 346    1      238    |
 | 235    235    4      | 9      1      68     | 367    378    238    |
 | 6      1      8      | 24*(3) 7      24*    | 5      34     9      |
 |----------------------+----------------------+----------------------|
 | 245    2456   56     | 1      24     3      | 8      9      7      |
 | 9      48     3      | 5      48     7      | 2      6      1      |
 | 7      28     1      | 6      28     9      | 34     345    35     |
 |----------------------+----------------------+----------------------|
 | 1      356    2      | 38     9      68     | 37     357    4      |
 | 38     9      7      | 24*    5      24*    | 1      38     6      |
 | 3458   3456   56     | 7      36     1      | 9      2      358    |
 *--------------------------------------------------------------------*

To complement daj95376 spotting the Unique Rectangle [24] in rows3 and 8 and columns4 and 6, the presence of candidate (3) in r3c4 aborts the formation of a "Deadly Pattern" whereby either of the two candidates [2] or [4] could be alternatively placed in the four cells marked * which would then produce two different solutions and hence an invalid puzzle. Therefore the placement of candidate 3 in r3c4 avoids the undesirable "Deadly Pattern".

Cec
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Postby mayres » Sat Mar 29, 2008 4:36 am

Thank you all so much for the help - I will study these and see if I can comprehend the hints. On the surface they are "over my head" but I will study and hopefully get there. Again - THANKS! mike
mayres
 
Posts: 24
Joined: 02 July 2007

Postby mayres » Sun Mar 30, 2008 4:58 am

Yea! I found the last post by Cec to actually be easy enough for my feeble mind to understand. It all made perfect sense and enabled me to proceed to the end without further issue. THANKS SO MUCH AGAIN!
mayres
 
Posts: 24
Joined: 02 July 2007

Help on black belt puzzle please

Postby Cec » Sun Mar 30, 2008 1:45 pm

mayres wrote:"Yea! I found the last post by Cec to actually be easy enough for my feeble mind to understand..."

Thanks to angusj, a good explanation of the xy-wing technique, which was also mentioned above, is described Here
I intended to include this in my previous post but only tracked it down today. Hope this also helps you.

Cec
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