Help solving - a clue

Advanced methods and approaches for solving Sudoku puzzles

Help solving - a clue

Postby janiv » Sun Jun 19, 2005 9:50 am

Hello, I have the following board:

*62 9*4 ***
*** 3** 4**
38* *** ***

*** *6* 3*4
6** 4*2 **7
2*9 *1* ***

*** *** *83
*91 **6 ***
*** 5*8 61*

I got till here

*62 9*4 *3*
9** 3** 4**
384 6** ***

*** 869 324
638 452 197
249 713 ***

**6 1*7 *83
891 236 745
**3 5*8 61*

Thanks,
Janiv Ratson.
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Postby simes » Sun Jun 19, 2005 10:12 am

You need a technique sometimes called "disjoint subsets."

Look at where 1, 5 and 7 can go in row 2. This allows you to eliminate some candidates and make a placement.
Last edited by simes on Sun Dec 11, 2011 2:34 pm, edited 1 time in total.
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Postby janiv » Sun Jun 19, 2005 10:33 am

how?
row2:
{9},{1,5,7},{5,7},{3},{2,8,7},{1,5},{4},{5,6,7},{1,2,6,8} !
how can I figuire something from this row ?
Thanks again,
Janiv Ratson.
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Postby george-no1 » Sun Jun 19, 2005 10:46 am

Hi Janiv

Simes is right, take a very close look at the cells r2c2, r2c3 and r2c6 and work out what are the only three digits that can go in these cells.

This is an excellent example of disjoint subsets (also known as a hidden triplet, in this case). For my explanation of disjoint subsets, click here, and scroll down.

Hope this helps,

George:)
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