Nightmare, Jan 30, 2006

Discuss the <a href="http://www.sudocue.net/daily.php">Daily Sudoku Nightmare</a> here
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Shahrazad
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Nightmare, Jan 30, 2006

Post by Shahrazad »

Brute force solving needed ???

ugh :evil:


Greetz,
Shah
Leo
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Post by Leo »

Shah, staan je solver instellingen wel goed, want bij mij geeft ie dat niet aan.

Niet dat ik hem opgelost heb hoor? Tegenwoordig kijk ik hoe ver ik kom en dan ga ik met de log verder. Kijken wat er nog te leren valt. Anders gaat er mij wat teveel tijd inzitten.
In Dutch, Leo wrote:Shah, are your solver settings correct, because with me {Sudo Cue} does not show this.

Not that I solved it. Nowadays I'll see how far I can get, and then I'll continue using the {Sudo Cue} log. To see what I can learn from it. Otherwise I spend too much time on it.
Leo, die ook van Sudoku's houdt.
David Bryant
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What's that, Leo?

Post by David Bryant »

Can someone explain what Leo said? I don't speak Dutch, and I can't read it, either.

Shah, the best I can do is concentrate on the connection between the "9"s and "5"s in this puzzle. Setting r5c9 = 9 cracks the puzzle wide open. Ruling out the possibility of a "9" at r5c1 seems to be a bit tricky, though. dcb
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Post by Leo »

Thanks for translation Ruud. I means that I was in the Dutch area.
Leo, die ook van Sudoku's houdt.
Shahrazad
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Post by Shahrazad »

My Solver settings are as below:

Image

And the log shows this:

Image

What gives ? what is wrong with my settings ?

Greetz
Shah
Shahrazad
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Re: What's that, Leo?

Post by Shahrazad »

David Bryant wrote:Shah, the best I can do is concentrate on the connection between the "9"s and "5"s in this puzzle. Setting r5c9 = 9 cracks the puzzle wide open. Ruling out the possibility of a "9" at r5c1 seems to be a bit tricky, though. dcb
I guess that is the Brute Force step that accomplishes that :?:

Greetz
Shah
Ruud
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Post by Ruud »

Brute Force is not required in my Nightmares.

Very deep logic, that's what's needed.

This Nightmare requires a step, that is not yet implemented in Sudo Cue, but would have been caught by the template check, which you disabled, Shah.

It goes like this:

Image

I've used 3 different colors for the candidates in row 9. The 3 colors are green, yellow and blue. The 2 red colored candidates have to go in each of the 3 cases. So, R1C2 is forced under all circumstances.

Well, I never claimed they would be easy, did I?

Ruud.
“If the human brain were so simple that we could understand it, we would be so simple that we couldn't.” - Emerson M Pugh
lac
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2 red coloured candidates?

Post by lac »

I don't see how you got to the point of knowing there were 2 red
coloured candidates in row 1.

For what it is worth, I was trying to proove that c5r7 was 4 or 7, but
after hours of this I couldn't. I ended up proving that c1r9 could not
be 6. This frustratingly did not give me any other solved cells but
itself. However, I then proved that c1r8 could not be 6 either, which
solved things. But while I thought I had heuristic for determining
which cells are best to attack, it wouldn't have suggested that one.

Laura
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Post by Ruud »

lac wrote:I don't see how you got to the point of knowing there were 2 red
coloured candidates in row 1.
I knew because Sudo Cue told me there was a template elimination, which eliminated 5 candidates in a single step. All I had to do is figure out why this was the case. It did take me some time to figure this one out.

Ruud.
“If the human brain were so simple that we could understand it, we would be so simple that we couldn't.” - Emerson M Pugh
Shahrazad
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Post by Shahrazad »

This is getting way beyond my limited capabilities

I guess the Nightmares have outgrown me now.

These techniques are fine to use in computerprograms, but my brains aren't built for that. I can't make them, plain and simple.

Also, it's taking me too much time to attempt to solve them, and I can't neglect my work and get fired :?

I guess, I have to leave it to the pro's

Cya around all :)
Shah
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Ruud's "Template" idea is really pretty neat!

Post by David Bryant »

Laura wrote:I don't see how you got to the point of knowing there were 2 red coloured candidates in row 1.
I have to admit I didn't spot this right at first, but now that Ruud has pointed it out I think it's pretty slick.
A new kind of formation! Thanks, Ruud!

There are only three places for a "7" in row 1. There are only two places for a "7" in row 5. There are only
three places for a "7" in row 9. And there are only two places for a "7" in column 2.

The way the possible "7"s line up in rows 1, 5, & 9 almost make a "swordfish" pattern, but not quite
(r1c2 across from r9c3). The neat thing is, no matter where the "7" appears in row 9, there must be a "7" at r1c2.

It's not a "double-implication chain" -- it's a "triple-implication chain" of sorts. Beautiful! dcb
lac
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Beautiful

Post by lac »

It is rather beautiful at that. Thank you.

Laura
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