Trouble with this sudoku, which is the next logical step?

Post the puzzle or solving technique that's causing you trouble and someone will help

Trouble with this sudoku, which is the next logical step?

Postby Jackie78 » Sat Mar 08, 2008 9:44 pm

Hi,

I am currently having trouble with this sudoku, which I have solved so far, but simply cannot find the next logical step without having to guess. Can you please help?

Code: Select all
--------------------------
| x x x | 4 2 x | x x 7 |
| x 7 2 | 1 8 6 | 5 3 x |
| x x x | 7 5 x | x 2 x |
--------------------------
| x x x | 6 4 2 | 3 7 x |
| 2 x x | 5 7 1 | 8 x x |
| x 6 7 | 9 3 8 | x 5 2 |
--------------------------
| 7 x x | 8 6 4 | 2 9 3 |
| 6 2 9 | 3 1 5 | 7 x x |
| 3 4 8 | 2 9 7 | 6 1 5 |
--------------------------

The Original one I found here: http://sudoku.zeit.de/sudoku/kunden/die_zeit/pdf/sudoku_2008-03-06_schwer.pdf

Thanks for your help:)
Jackie78
 
Posts: 7
Joined: 08 March 2008

Postby StrmCkr » Sat Mar 08, 2008 10:01 pm

where are you stuck on this puzzle.?

that would help.

candidates grid.

like this.

Code: Select all
 *--------------------------------------------------------------------*
 | 1589   13589  1356   | 4      2      39     | 19     68     7      |
 | 49     7      2      | 1      8      6      | 5      3      49     |
 | 1489   1389   1346   | 7      5      39     | 149    2      14689  |
 |----------------------+----------------------+----------------------|
 | 1589   1589   15     | 6      4      2      | 3      7      19     |
 | 2      39     34     | 5      7      1      | 8      46     469    |
 | 14     6      7      | 9      3      8      | 14     5      2      |
 |----------------------+----------------------+----------------------|
 | 7      15     15     | 8      6      4      | 2      9      3      |
 | 6      2      9      | 3      1      5      | 7      48     48     |
 | 3      4      8      | 2      9      7      | 6      1      5      |
 *--------------------------------------------------------------------*


theres a pointing pair on column 3 (1&5)
removes 1&5 from R1,3C3

theres a Hidden pair in box 3 (8/6)
wich exposes a locked candidate 1 (R1C7 &R3C7) in box 3 forces
r6c7 = 4

puzzles reduces to singles at this point.
Some do, some teach, the rest look it up.
User avatar
StrmCkr
 
Posts: 626
Joined: 05 September 2006

Postby Pat » Sun Mar 09, 2008 9:34 am

Jackie78 wrote:
I am currently having trouble with this sudoku, which I have solved so far, but simply cannot find the next logical step

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



The original one I found here: http://sudoku.zeit.de/sudoku/kunden/die_zeit/pdf/sudoku_2008-03-06_schwer.pdf


hi Jackie78,

in box 6,
the 9 is in column 9
-- exclude 9 elsewhere in that column
User avatar
Pat
 
Posts: 3423
Joined: 18 July 2005

Trouble with this sudoku, which is the next logical step?

Postby Cec » Sun Mar 09, 2008 10:20 am

Hi Jackie78,

There are a number of links which explain the basic solving techniques such as "Locked Candidates" (1) and (2) (also known as "Pointing Pairs"), "Singles", "Naked Pairs", "Triples", etc. You could try these...

http://www.angusj.com/sudoku/hints.php
http://www.sadmansoftware.com/sudoku/techniques.htm
http://www.scanraid.com/BasicStrategies.htm

The procedure for posting puzzles, including the Pencilmark Grid, is described Here

Happy sudoku solving:)

Cec
Cec
 
Posts: 1039
Joined: 16 June 2005


Return to Help with puzzles and solving techniques