Need help... Don't understand this hint.

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Need help... Don't understand this hint.

Postby kingnautilus » Mon Feb 27, 2006 3:47 am

edit: reposted image so that candidates are showing

I don't understand the hint... "exclude based on naked pairs."

I know that the fourth and fifth cells in that box are either 2 or 9, and that the seventh and ninth cells in that box are either 5 or 7.

Please help, thanks.
Last edited by kingnautilus on Sat Mar 04, 2006 4:43 pm, edited 1 time in total.
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Postby Carcul » Mon Feb 27, 2006 11:30 am

Hi Kingnautilus.

It would be more easier for us to help you if you post directly your puzzle as text, because in the image in your link the candidates cannot be seen.

Regards, Carcul
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Re: Need help... Don't understand this hint.

Postby Cec » Mon Feb 27, 2006 1:46 pm

kingnautilus wrote:"...I know that the fourth and fifth cells in that box are ...".

Hi Kingnautilus,
As well as posting the puzzle as suggested by carcul if you click on this Thread you can read up on the procedures for posting puzzles including the recommended Terminology for defining box numbers, cell positions, etc.

For example, the grid has nine 3x3 boxes and "that" box you refer to would be box2. The cells you mention having candidates 2 or 9 (also known as pencilmarks) are presumably cells row2column4 (r2c4) and r2c5 whilst the cells containing candidates 5 and 7 would presumably be r3c4 and r3c6. I realize in this instance that such identification is possible but highly unlikely when trying to define numerous cells to readers for a complex puzzle. As the saying goes, the chorus sounds better when we use the same music sheet:)

Cec
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Postby kingnautilus » Sat Mar 04, 2006 8:43 pm

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Postby MCC » Sun Mar 05, 2006 12:19 pm

There is a naked pair of 5,6 in box 6 column 9 that will enable you to eliminate the 6 in r5c7.


The 6 in r5c7 could also be eliminated by the x-wing in:
r5c1,r5c9
r6c1,r6c9

Also the x-wing in:
r3c7,r3c8
r7c7,r7c8


Then to continue there is a uniqueness rectangle of 1,2 in boxes 4 and 7

MCC
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re: Don't understand this hint

Postby Pat » Sun Mar 05, 2006 12:29 pm

kingnautilus wrote:
I don't understand the hint
"exclude based on naked pairs"


in box 6,
you see 2 cells which can only be { 5,6 }
- therefore, exclude these digits elsewhere in that box.

this creates a new duo:
in r5,
there are now 2 cells which can only be { 1,2 }
- therefore, exclude these digits elsewhere in that row.

now in box 5,
the 2 must be in c5
- therefore, exclude 2 elswhere in that column
and you've finally settled r2.

~ Pat
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