Help please

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Help please

Postby deecee » Mon May 22, 2006 6:46 pm

I am stuck on the following puzzle. Have I missed an obvious move? This is as far as I have got: Can anyone help please

3-2 9-- -7-
1-- --7 --6
97- -2- 8--

8-- --- ---
247 591 368
6-- --- --1

4-3 -6- 587
5-- 47- ---
72- --5 649
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Postby tarek » Mon May 22, 2006 6:53 pm

Look for something HIDDEN in Row 2.

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Postby Karlson » Mon May 22, 2006 6:54 pm

First there is an naked triple in Row 8
Secondly we have a naked quad in Row 2

A few Box-Line-Reductions follow after that and the rest is trivial...

I hope I could help you with that - ask if some terms I used are not clear.

Regards,
Karlson

edit: ah I saw Tarek's post - hope I didnt say too much ;)
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Postby deecee » Mon May 22, 2006 7:17 pm

Thanks for your help. Is the quad in row 2 in columns 2,3,4 and 5? So I can delete candidates 3 and 5 from row 2, column 8, and candidate 4 from row 2 column 7? Am I on the right track?
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Postby kevinzhong2001 » Mon May 22, 2006 7:32 pm

You are on the right track, but it doesn't help much.
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Re: Help please

Postby Cec » Tue May 23, 2006 3:56 am

deecee wrote:I am stuck on the following puzzle. Have I missed an obvious move? This is as far as I have got: Can anyone help please

Hi deecee and welcome to the forum,

It's a good idea to always submit both the original puzzle and the stage you have reached which enables us to detect whether you have erred in reaching your current position. Click on Here to read up on the procedures for posting puzzles.

After the above exclusions your candidate grid will look like this:
Code: Select all
 
 *-----------------------------------------------------------*
 | 3     568   2     | 9     1458  468   | 14    7     45    |
 | 1     58    458   | 38    3458  7     | 29    29    6     |
 | 9     7     456   | 136   2     346   | 8     135   345   |
 |-------------------+-------------------+-------------------|
 | 8     1359  159   | 2367  34    2346  | 2479  259   245   |
 | 2     4     7     | 5     9     1     | 3     6     8     |
 | 6     359   59    | 2378  348   2348  | 2479  259   1     |
 |-------------------+-------------------+-------------------|
 | 4     19    3     | 12    6     29    | 5     8     7     |
 | 5     1689  1689  | 4     7     2389  | 12    123   23    |
 | 7     2     18    | 138   138   5     | 6     4     9     |
 *-----------------------------------------------------------*


The "naked triple" [12] [123] and [23] in row8 (r8) enables any other 1's, 2's and 3's to be excluded from r8. In box3 (upper right 3X3 box) notice the 3's are "locked" in r3 of that box. This enables all other 3's outside that box to be excluded from r3.
Look at column6 (c6) and try spotting another example of "Locked" candidates which can lead to the exclusion of other candidates in box 5.

The following sites (just click on them) are popular for basic solving techniques:
http://www.angusj.com/sudoku/hints.php
http://www.sadmansoftware.com/sudoku/techniques.htm
http://www.scanraid.com/BasicStrategies.htm

Good luck with your sudoku.

Cec
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Postby deecee » Tue May 23, 2006 10:24 pm

I had more or less got to that stage of candidate reduction before I got stuck. Thanks for your help. I have now solved the puzzle.
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