## Is there a triple here?

Advanced methods and approaches for solving Sudoku puzzles

### Is there a triple here?

Column 1 of Daily Sudoku, 28 July 05:

(1,2,6)
8
(1,2,6,7)
3
5
9
(1,2,6)
(2,6,7)
4

Can I eliminate the 7 in R3, making the 1,2,6 a triple? Does this follow logically?

I'm just getting started with the puzzles, so working my way thru a hard one slowly & with a bit of confusion.

thanks, T
wdcbrucefan

Posts: 2
Joined: 25 July 2005

No. It could go (for example):

1
8
7
3
5
9
2
6
4
PaulIQ164

Posts: 533
Joined: 16 July 2005

A triple occurs when exactly 3 cells in a row, column or 3x3 box must contain exactly 3 specific numbers, meaning that these 3 numbers can be deleted from all other cells in that row, column or 3x3 box. For instance, in the row:

136 136 1379 l 36 8 4 l 369 12 5

There is a triple with 1, 3 and 6, marked in red.

You can therefore delete 1, 3 and 6 from all non-red cells, leaving

136 136 79 l 36 8 4 l 9 2 5 l

Now the 9 can be deleted from cell 3 in this row, leaving

136 136 7 l 36 8 4 l 9 2 5

Hope this helps.

George
george-no1

Posts: 150
Joined: 20 May 2005

George,
Why doesn't there have to be a "1" with the 36 in the middle 3x3 box?
Sorry for the basic question, but i am trying to learn and understand.

Regards,
George
nj3h

Posts: 47
Joined: 07 July 2005

Good question, nj3h.

In my explanation, I said "exactly 3 cells in a row, column or 3x3 box must contain exactly 3 specific numbers"

This example works because those three cells contain a combination of the numbers 1, 3 and 6 and no other numbers. This means that the 1, 3 and 6 must be spread across those three cells alone and can therefore be deleted from any other cells in the row.

If you don't understand, I'd be happy to explain in a little more detail, just say the word.

George
george-no1

Posts: 150
Joined: 20 May 2005

To be wordy about it, it's basically saying:

"If this cell here can contain 1, 3 or 6, and the same for this cell over here, oh, and that cell can contain only 3 or 6 - then whatever combination I (randomly and without thinking) might fill in these cells, they're going to be full of the numbers 1, 3 or 6."

Geddit?

Which means that 1, 3 or 6 can't be anywhere else.

Doesn't it?

But if you chucked an extra option in, like the third cell not only containing 3 and 6, but also containing, say, an 8. Well, then that b**gers the whole idea up.
Karyobin

Posts: 396
Joined: 18 June 2005

I'd add one more, important, word to what Karyobin said: ""If this cell here can contain only 1, 3 or 6....
Doyle

Posts: 61
Joined: 11 July 2005

Karyobin,

I like the way you just repeated exactly what I said, starting with an oxymoron

Karyoooooooobin wrote:To be wordy... it's basically...

and add a few mild swear words

Karyoooooooobin wrote:That b**gers the whole idea...

and add a few rhetorical questions that are spelt as said

Karyoooooooobin wrote:Geddit?

And suddenly everyone understands the idea.

George
george-no1

Posts: 150
Joined: 20 May 2005

'zackly! 's what teachin's all about. Tell 'em, then tell 'em again loudly. Then simplify it. Then send somebody out for being stupid. Then insist that everybody understands 'coz it's too mindlessly obvious to explain in any other way.

There's very few kids will own up to not gettin' it after that lot.

Job done.
Karyobin

Posts: 396
Joined: 18 June 2005

You analysed it well, young padawan. Maybe you could do my job, seein' as I've quit.

And it's pronounced 'oh', not 'ooooooo' (?!)
Karyobin

Posts: 396
Joined: 18 June 2005

Sorry, I was just having a little laugh because I like the letter 'o'. It's a hilarious letter, don't you think?

So, you're a teacher then! Maths, I presume? I don't think I could do your job, as I'm pretty sure teachers have to be over 18 and have some kind of qualification. But I have taught Maths to some people in my class before. I think they understood (I used lots of different lovely colours, like in my explanation of triples above), but next time I'll try your method.

Geooooooooooooooorge
george-no1

Posts: 150
Joined: 20 May 2005