Fiendish one

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Fiendish one

Postby markb » Thu Dec 29, 2005 5:36 pm

Hi everyone,

Just had some advice from the forums that I should post a puzzle here for advice on how to progress......

First post was -

"I have got as far as the fiendish puzzles.....

...but can't finish one.

I get to the stage were I have to guess at one a number going into 1 of 2 boxes. I thought that you could always get the next number through logic?? It is only when putting the last few (say 4 - 6) numbers in that the mistake becomes apparent.

So my questions are 'Can you always get the next number through logic?'.
and 'Where can I learn the technique?'. "

Puzzle is

**9|8*7|**2
***|312|8**
2*8|6*9|***
854|723|**1
**1|468|325
623|591|748
**2|176|4*3
**7|285|***
1**|934|2**

I get this far with all the fiendish puzzles and then can't get further!?!?!?!

Any help with getting past this stage would be great!

Thanks
Mark
markb
 
Posts: 12
Joined: 27 December 2005

re: duo

Postby Pat » Thu Dec 29, 2005 5:53 pm

markb wrote:
Code: Select all
 . . 9 | 8 . 7 | . . 2
 . . . | 3 1 2 | 8 . .
 2 . 8 | 6 . 9 | . . .
-------+-------+------
 8 5 4 | 7 2 3 | . . 1
 . . 1 | 4 6 8 | 3 2 5
 6 2 3 | 5 9 1 | 7 4 8
-------+-------+------
 . . 2 | 1 7 6 | 4 . 3
 . . 7 | 2 8 5 | . . .
 1 . . | 9 3 4 | 2 . .

the 5,8 for box 9
have only 2 cells available!

reserve these cells for the 5,8
- this leaves just one cell for the 7 in that box

- Pat
User avatar
Pat
 
Posts: 3440
Joined: 18 July 2005

Alright!

Postby markb » Thu Dec 29, 2005 6:04 pm

Ok thanks for that.....

Let me just ask you another one.....

(I presume boxes are 123
456
789)
?

Hidden pair in box 1 = 4 + 5 in cell 1 & 4.
Means that 3 in box 1 must be in middle column.
Means that 3 in box 7 must be in cell 4 (choice of cells 4 & 5).

It's not though......?

Cheers
Mark
markb
 
Posts: 12
Joined: 27 December 2005

Do'h!

Postby markb » Thu Dec 29, 2005 6:09 pm

Sorry about this......think I just misunderstood what a hidden pair was...is......gawd..............
markb
 
Posts: 12
Joined: 27 December 2005

Re: Fiendish one

Postby tso » Thu Dec 29, 2005 6:34 pm

markb wrote:"I have got as far as the fiendish puzzles.....

...but can't finish one.


When you come to a stand still, fill in all possible candidates in each unsolved cell. Read the tutorials at Simple Sudoku, Sadman Sudoku and Sudoku Susser (You have to download Susser to get the PDF tutorial. You don't have to install it -- but all three of these software apps are very good learing tools.) Read these forums, work through examples. To search in this forum, use GOOGLE, click on advanced search and restrict the domain to sudoku.com.

markb wrote:I get to the stage were I have to guess at one a number going into 1 of 2 boxes. I thought that you could always get the next number through logic?? It is only when putting the last few (say 4 - 6) numbers in that the mistake becomes apparent.

So my questions are 'Can you always get the next number through logic?'. and 'Where can I learn the technique?'. "


It is always possible for each and every Sudoku to be solved by logic and there are always many paths to the solution. There is no one technique, no magic bullet. It is also possible for a puzzle to be beyond the skills of any individual person. It is not possible to create a Sudoku that requires guessing anymore than you can create a crossword puzzle that requires guessing. Having mastered arithmetic, a student shouldn't be frustrated in not being able to solve problems that require calculus.

markb wrote:Puzzle is

**9|8*7|**2
***|312|8**
2*8|6*9|***
854|723|**1
**1|468|325
623|591|748
**2|176|4*3
**7|285|***
1**|934|2**



Here's your puzzle:
Code: Select all
 . . 9 | 8 . 7 | . . 2
 . . . | 3 1 2 | 8 . .
 2 . 8 | 6 . 9 | . . .
-------+-------+------
 8 5 4 | 7 2 3 | . . 1
 . . 1 | 4 6 8 | 3 2 5
 6 2 3 | 5 9 1 | 7 4 8
-------+-------+------
 . . 2 | 1 7 6 | 4 . 3
 . . 7 | 2 8 5 | . . .
 1 . . | 9 3 4 | 2 . .



The candidates lists:

Code: Select all
  345   1346  9     | 8     45    7     | 156   1356  2     
  457   467   56    | 3     1     2     | 8     5679  4679 
  2     1347  8     | 6     45    9     | 15    1357  47   
 -------------------+-------------------+-------------------
  8     5     4     | 7     2     3     | 69    69    1     
  79    79    1     | 4     6     8     | 3     2     5     
  6     2     3     | 5     9     1     | 7     4     8     
 -------------------+-------------------+-------------------
  59    89    2     | 1     7     6     | 4     589   3     
  349   3469  7     | 2     8     5     | 169   169   69   
  1     68    56    | 9     3     4     | 2     5678  67   



Look in box 9. Row 8 columns 7,8,9 form a naked triple [169]. This excludes 1s, 6s and 9s from the rest of box 9 and from the rest of row 8. Nothing but singles is required after this.
tso
 
Posts: 798
Joined: 22 June 2005

Thanks everyone!

Postby markb » Fri Dec 30, 2005 11:52 am

I managed to solve this one after the advice from Pat.
I've started to have a look at the other sites you mentioned - thanks for all the advice etc!

Cheers
Mark
markb
 
Posts: 12
Joined: 27 December 2005


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