Help with completion of hard puzzle

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Help with completion of hard puzzle

Postby RichardS » Tue Jan 24, 2006 8:59 am

Hi All,

Have a puzzle that I have gotten so far and no more, and am looking for some advice about finishing it.

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


After some manipulation you get:
Code: Select all
457  9      14   | 156   167  57   | 3   2    8 
3    18     6    | 2     18   4    | 9   7    5
4578 1458   2    | 1358  9    3578 | 14  14   6
-----------------+-----------------+-------------
48   6      3    | 9     5    1    | 7   48   2
2    7      9    | 38    4    38   | 5   6    1
1    48     5    | 7     2    6    | 48  9    3
-----------------+-----------------+-------------
458  12458  148  | 158   3    2578 | 6   158  79
6    3      18   | 4     178  5789 | 2   158  79
9    1258   7    | 1568  168  258  | 18  3    4


I am now stuck with the next move(s). Where to now?

regards,
Rich
RichardS
 
Posts: 4
Joined: 23 January 2006

Postby Carcul » Tue Jan 24, 2006 9:14 am

Hi RichardS.

You have a naked pair in row 3 in cells r3c7/r3c8. See if you can solve from here.

Regards, Carcul
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Re: Help with completion of hard puzzle

Postby Cec » Tue Jan 24, 2006 10:21 am

richards wrote:"..looking for some advice about finishing it.."


Hi Richard and welcome to the Forum,
To complement Carcul's help, in row 3 there is a "naked pair" [14] in box 3 (the puzzle grid contains nine 3X3 'boxes' and are identified as numbered 1 to 9). This means all other candidates 1 and 4 in this row can be excluded.

In column 3 notice that candidate 8 must go either in r7c3 or r8c3 - it doesn't matter at this stage which of these two cells the 8 must go. Because these candidate 8's are "locked" in column 3 of box7 then the remaining candidate 8's within box7 can be excluded. This is another of a number of basic solving techniques which are explained by clicking on HERE and HERE

Try spotting the "naked quad" in row 7 (the same four numbers or a combination thereof appearing in only four cells) which enables any of these same candidates to be excluded if existing in other cells of this row..The rest of the puzzle can be solved by identifying "hidden" or "naked" singles.

If you are still stuck then ask for further help.

Cec
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Postby RichardS » Tue Jan 24, 2006 4:48 pm

Thanks for the help guys.

Will let you know if I need more help:)

Rich
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Posts: 4
Joined: 23 January 2006

Re: Help with completion of hard puzzle

Postby RichardS » Tue Jan 24, 2006 5:12 pm

cecbevwr wrote:Try spotting the "naked quad" in row 7 (the same four numbers or a combination thereof appearing in only four cells)


Just for a check, is the naked quad you are refering to 1458?

regards,
Rich
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Posts: 4
Joined: 23 January 2006

Postby MCC » Tue Jan 24, 2006 5:31 pm

Yes it is.

MCC
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Postby RichardS » Wed Jan 25, 2006 9:15 am

Great, thanks all:)

Solved it.

Rich
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Posts: 4
Joined: 23 January 2006


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