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Zoelly · Joined: 15 Mar 2009 Posts: 8

Does this puzzle require any solution techniques beyond the basics: finding pairs, hidden pairs, box-line reduction, or row claiming?

wapati · Posted: Sun Mar 15, 2009 5:39 am Post subject:

Zoelly · Joined: 15 Mar 2009 Posts: 8

thanks!
i'll keep studying the numbers

storm_norm · Joined: 18 Oct 2007 Posts: 1741

the answer to that question is yes !!

there is a hidden pair in this puzzle that I believe you need to find.
as well as a couple intersections

Zoelly · Joined: 15 Mar 2009 Posts: 8

I think you might be right, Norm.
Hidden pairs can be so hard to find.
I don't know the term "intersection."

So far I've done FOUR Box-Line Reductions in this puzzle.
1) In Box 1 because of numbers required in Row 1.
2) In Box 3 because of numbers required in Col 9.
3) In Box 7 because of numbers required in Col 1.
4) In Box 9 because of numbers required in Col 9.

Naked pair in Col 5.
Naked pair in Col 4. These were easy.

There was "row claiming" in Box 9 - Row 9.

There was a hidden pair in Box 9.

With all that I've only solved four squares. It's making me cross-eyed!

Marty R. · Posted: Tue Mar 17, 2009 4:03 am Post subject:

Zoelly · Joined: 15 Mar 2009 Posts: 8

8 . . |3 7.|. 4 .
. 6 4|. . 1|. . .
. 7 9|. 6 .|. . 2
-----+----+-----
4 . .|7 5 2|. . 8
2 . .|. 1 . |. . 7
7 . .|6 9 .|. . 1
----+---- +-----
9 . .|. 3 .|5 . .
. . . |5 . .|. 1 .
. 8 .|. 4 7|. . 3

This is my current status.[/b]

Marty R. · Posted: Wed Mar 18, 2009 5:14 am Post subject:

storm_norm · Joined: 18 Oct 2007 Posts: 1741

in the state of the puzzle posted by marty, it is possible to make it through without hidden pairs.
although there is one present in box 9 as it is.

marty,
do you see the hidden pair in box 9?

whenever my eyes find a candidate that only exists twice in a box row or column, then I look for partner candidate that also exists only twice in those same cells.

nataraj · Posted: Wed Mar 18, 2009 6:42 am Post subject:

A starting point would be the naked pair 48 in col 4
Plus: "3" in box 1, "5" in box 6 and "6" in box 4.

The hidden pair 78 in box 9 is a toughie (I never find hidden pairs anyway - sometimes not even hidden singles, shame, but the complementary naked quad 2469 is not too obvious, either Sad

)

oops, cross post. didnt see norm's diagram.

storm_norm · Joined: 18 Oct 2007 Posts: 1741

Marty R. · Posted: Wed Mar 18, 2009 3:47 pm Post subject:

storm_norm · Joined: 18 Oct 2007 Posts: 1741

Marty,
since you claim to have never found a hidden pair, the diagram gives you a chance to see one.

Marty R. · Posted: Wed Mar 18, 2009 5:31 pm Post subject:

Zoelly · Joined: 15 Mar 2009 Posts: 8

Hi Ho!
I've solved the puzzle!

Thanks to Nataraj, especially, for telling me to look at 3's in box 1. There were so many 3's scattered about in this puzzle that I must have just started to ignore them.

This was one nicely constructed puzzle!

As I noted earlier,"There was a hidden pair in Box 9," I had already found the hidden pair 78.

What I want to know, Marty, is how to distinguish which boxes are making up the naked quad 2469.

Norm, I must honestly admit that I have no clue what all those 8's highlighted in red are showing me. I'm sure it's useful knowledge.

Zoelly

Zoelly · Joined: 15 Mar 2009 Posts: 8

Norm,
Well, I kinda do know about all the red 8's, I think!

Is that to show you're eyeballing them --- because you're working on the theory that they're part of a hidden pair?
Green 7's, the same?

Some 8's are highlighted, some are not. On purpose or accidental?
Zoelly

Marty R. · Posted: Thu Mar 19, 2009 4:42 am Post subject:

Zoelly · Joined: 15 Mar 2009 Posts: 8

When naked quads are made of subsets like those seen in box 9, I don't spot them easily. I'm glad you pointed them out for me, Marty.

It's that the 4 appears in only two squares and the 2 appears in only two squares. I wouldn't think to associate them right off. But I do see that they are all subsets of 2469. Tricky!

I'll need more practice to look for them. So in the center box of this puzzle, Box 5, 1348 constitutes an example of naked quads? (Although it doesn't help to solve anything.) If I can begin to recognize them, it's a start.

Zoelly