Stumped and Bewildered

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Stumped and Bewildered

Postby JSC4490 » Tue May 30, 2006 7:58 am

Alright so i got stuck on this puzzle from Sudoku for Dummies-Puzzle 240: Diabolical. =P

|6**|7**|3**| |8**|5**|1**| |2**|9**|4**|
|48*|48*|5**| |9**|6**|2**| |1**|37*|37*|
|29*|1**|29*| |3**|7**|4**| |8**|6**|5**|

|42*|5**|1**| |6**|8**|9**| |7**|342|32*|
|7**|428|298| |1**|3**|5**| |49*|428|6**|
|89*|3**|6**| |2**|4**|7**| |5**|1**|89*|

|1**|9**|78*| |4**|2**|6**| |3**|5**|78*|
|3**|6**|27*| |5**|1**|8**| |49*|427|279|
|5**|28*|4**| |7**|9**|3**| |6**|28*|1**|
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Postby Hud » Tue May 30, 2006 3:52 pm

I'm not very good at colouring, but I believe that'll solve this nicely. I colored the 8s starting in box 6. The only way I could make a valid assumption was if row6col9 were true (8). If it were false, the assumption would be invalid. I'm sorry for the vague explanation, but I believe it works out right.
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Postby underquark » Tue May 30, 2006 4:54 pm

If r6c9=9
Then r6c1=8, r2c2=8, r9c2=2, r9c8=8
Leaves r5 with too many 4s or no place for an 8
So r6c9 must be 8
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Re: Stumped and Bewildered

Postby Cec » Wed May 31, 2006 10:18 am

Just out of curiousity - with all the asterisks shown, was this a "normal" 9X9 sudoku or a 27X27 sudoku puzzle?
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re: Sudoku for Dummies - Puzzle 240

Postby Pat » Wed May 31, 2006 11:00 am

JSC4490 wrote:i got stuck on this puzzle from Sudoku for Dummies - Puzzle 240: Diabolical
Code: Select all
 6   7   3   | 8   5   1   | 2   9   4   
 48  48  5   | 9   6   2   | 1   37  37   
 29  1   29  | 3   7   4   | 8   6   5   
-------------+-------------+------------
 42  5   1   | 6   8   9   | 7   342 32   
 7   428 298 | 1   3   5   | 49  428 6   
 89  3   6   | 2   4   7   | 5   1   89   
-------------+-------------+------------
 1   9   78  | 4   2   6   | 3   5   78   
 3   6   27  | 5   1   8   | 49  427 279 
 5   28  4   | 7   9   3   | 6   28  1   

Cec: this seems to be a standard-size SuDoku,
with the possibilities shown in each cell.


proof-by-contradiction:
if c1 8 in r6,
then c3 8 in r7,
and c9 has no 8.
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Stumped and Bewilded

Postby Cec » Wed May 31, 2006 2:42 pm

Pat wrote:Cec: this seems to be a standard-size SuDoku,
with the possibilities shown in each cell..."

Thanks Pat. I thought it was a standard-size but the asterisks confused me. In hindsight I should have asked JSC4490 to clarify that it was a standard-size. Hopefully this post will be seen by JSC4490 who may wish to read up on how to post puzzles by clicking on HERE. "Coloring" of the 8's is also another way to solve the puzzle as pointed out above by Hud. On my reckoning the two negative 8's in Box 4 of the following grid means the positive 8's are "true" resulting in the exclusion of all negative 8's from cells r2c2, r5c3, r5c8,r6c1, r7c9 and r9c2.
Code: Select all
 6   7   3   | 8   5   1   | 2   9   4   
 48+ 48- 5   | 9   6   2   | 1   37  37   
 29  1   29  | 3   7   4   | 8   6   5   
-------------+-------------+------------
 42  5   1   | 6   8   9   | 7   342 32   
 7   428+298-| 1   3   5   | 49  428- 6   
-89  3   6   | 2   4   7   | 5   1  +89   
-------------+-------------+------------
 1   9   78+ | 4   2   6   | 3   5   78-
 3   6   27  | 5   1   8   | 49  427 279 
 5   28- 4   | 7   9   3   | 6   28+ 1   

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Postby tarek » Wed May 31, 2006 8:10 pm

The elimination mentioned can be achieved using the Finned X-wing (Sashimi variation, or the Eyless fish as I would like to name it from now on:D )
Code: Select all
*-----------------------------------------------*
| 6    7    3   | 8    5    1   | 2    9    4   |
| 48   48   5   | 9    6    2   | 1    37   37  |
| 29   1    29  | 3    7    4   | 8    6    5   |
|---------------+---------------+---------------|
| 24   5    1   | 6    8    9   | 7    234  23  |
| 7    248 *289 | 1    3    5   | 49  *248  6   |
| 89   3    6   | 2    4    7   | 5    1    89  |
|---------------+---------------+---------------|
| 1    9   #78  | 4    2    6   | 3    5    78  |
| 3    6    27  | 5    1    8   | 49   247  279 |
| 5   -28  *4   | 7    9    3   | 6   *28   1   |
*-----------------------------------------------*
Eliminating 8 From r9c2 (Eyeless Finned XWing in Columns 38 with 1 fin in Box 7)
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Stumped and Bewilded

Postby Cec » Thu Jun 01, 2006 3:17 am

tarek wrote:"... or the Eyless fish as I would like to name it from now on:D

tarek, If this suggested name is related to a "fish without eyes" the spelling should be "Eyeless fish":)

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Postby tarek » Thu Jun 01, 2006 12:41 pm

The fish missed an EYE & I missed an E......Typing mistake....The Eyeless in the code box below is correct....

Thanx Cec

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Postby underquark » Thu Jun 01, 2006 4:36 pm

So, it's official then; this is a "fsh"? What next; a blind deer (no idea)?
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Postby tarek » Thu Jun 01, 2006 4:51 pm

There is a Headless Finned Fish [The one with no Vertices on the elimination line, another Sashimi variation, not that common though]:)

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Another Solution

Postby Carcul » Thu Jun 01, 2006 6:52 pm

Almost Locked Sets XZ-rule:

A=[r8c39]: {2,7,9}; B=[r67c9]: {7,8,9}; x=9; z=7.

So, r8c8<>7 and the puzzle is solved.

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