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The N-Queens completion problem is NP-hard

122 pointsby t23over 7 years ago

11 comments

umanwizardover 7 years ago
The article completely misinterprets the press release[1].<p>The University of St Andrews isn&#x27;t offering a prize; they&#x27;ve just shown that the Queens puzzle on an n-by-n board (EDIT: actually, the n Queens completion puzzle) is NP-hard.<p>(By the way, even the press release, though less wrong than the article, is still pretty bad: apparently NP-complete problems are hard because they use &quot;backtracking&quot;. Also it seems to suggest that this is something computer programmers would solve, rather than mathematicians...)<p>[1]: <a href="https:&#x2F;&#x2F;phys.org&#x2F;news&#x2F;2017-09-simple-chess-puzzle-key-1m.html#jCp" rel="nofollow">https:&#x2F;&#x2F;phys.org&#x2F;news&#x2F;2017-09-simple-chess-puzzle-key-1m.htm...</a>
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rdiddlyover 7 years ago
Completely off-topic: As a one-time civil engineer, mathematical dullard, and frequent New York visitor, who is losing his mind, I thought this was about completing a subway line. In my defense, the N train does go to Queens (though it&#x27;s not called the N-Queens), and everybody knows completing a subway line is a really hard problem, especially if you&#x27;re following the story of the new 2nd Ave line.
anonetalover 7 years ago
The million-dollar prize just appears to be the Clay Institute&#x27;s prize for solving P vs NP. I am guessing that the queens problem (a special case of maximum independent set in a graph) is NP-Hard.
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imaginenoreover 7 years ago
It&#x27;s currently solved for up to N=27<p>Both 26 and 27 solutions came from supercomputers&#x2F;FPGAs and took months of compute time.<p><a href="http:&#x2F;&#x2F;www.nqueens.de&#x2F;sub&#x2F;WorldRecord.en.html" rel="nofollow">http:&#x2F;&#x2F;www.nqueens.de&#x2F;sub&#x2F;WorldRecord.en.html</a>
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Retricover 7 years ago
What you is fast in this case? If you can solve 1,000 x 1,000 in say 1 minute is that fast? Or do you need to solve 1,000,000 x 1,000,000 in a second?
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MichaelBurgeover 7 years ago
You can also claim the $1 million by being good at Mario and explaining your techniques:<p><a href="https:&#x2F;&#x2F;arxiv.org&#x2F;abs&#x2F;1203.1895" rel="nofollow">https:&#x2F;&#x2F;arxiv.org&#x2F;abs&#x2F;1203.1895</a>
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Zarathustover 7 years ago
Is there a proof somewhere which states that all NP hard problem can have a similar &#x2F; generic solution?<p>I find it more likely that the N-Queens problem will have a very specific solution
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andy_pppover 7 years ago
Can you find an algorithm to a problem that many believe would show that P == NP? Probably not.
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master_yoda_1over 7 years ago
Thanks for telling me that :)
sabujpover 7 years ago
ahh nqueens, this was my first real parallel program that I did using mpi
mathieubordereover 7 years ago
I don&#x27;t get why this article is getting attention here.