

Breaking np-complete with memcomputing. Is it real? - mhurd
http://meanderful.blogspot.com/2015/07/breaking-np-completeness-without-quantum.html

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krcz
> If we solve NP-complete efficiently then we may break TSP and all sorts of
> magical optimisation problems joyously drop out of the sky at our feet. It
> is not clear if this would also break integer factorisation and thus RSA,
> but perhaps it might.

Not true. Factorization is NP, so having a fast way of solving NP-complete
problem would yield a way to solve factorization as well. On the contrary it
is not known to be NP-complete (and is believed to not be), so solving
factorization in polynomial time would not help with other NP problems.

~~~
mhurd
Thanks.

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fractalcat
No, for the reason outlined by Aaronson in [0] - I don't see anything in the
update which addresses this.

[0]
[http://www.scottaaronson.com/blog/?p=2212](http://www.scottaaronson.com/blog/?p=2212)

~~~
mhurd
Interesting. I'm inclined to agree but I pause when I read that Scott Aaronson
still seems to hold the line on quantum computing not doing anything too
useful for NP-complete or a useful subset. The weight of opinion seems against
him on quantum though he remains empirically correct for the foreseeable
future.

~~~
jerf
"The weight of opinion seems against him on quantum though he remains
empirically correct for the foreseeable future."

Then you're misjudging the weights "for" and "against" him by putting _way_
too much weight on people who don't know what they're talking about and way
too little on those who do. It is likely that your "for" group are still
operating under the idea that "quantum" works by "trying all possible answers
then returning the correct one". This is empirically, mathematically-provably
wrong. Anyone operating under this idea deserves for you to weight them at
_zero_.

Despite the fact we still can't build a very big quantum computer, we actually
do know quite a bit about what they can do and not do. And as Scott Aaronson
points out _very_ frequently, if in fact they prove either able to do
something our current theories say they can not or unable to do something that
our current theories say they can, either way that will be very interesting,
_precisely_ because it will imply that there is something wrong with quantum
mechanics, which for all its "woo woo" reputation is one of the most solid
math-to-reality theories we have ever had in the history of mankind.

Scott Aaronson isn't "holding" the line... he and his fellow-travelers are
_drawing_ the line.

Edit: I'm also unsure on why you think Aaronson believes quantum "won't
work"... he's on the optimist side that quantum computers can be made
practical. If you mean that he doesn't think "quantum" can solve NP-
completeness, well, of course he doesn't... he understands the _mathematical
proof_ that it doesn't, so that's hardly surprising.

Edit edit: A positive followup to this negative message: Consider reading
Quantum Computing Since Democritus [1], or if you don't want to spend the
dough, read through the class notes that turned into that book [2].

[1]: [http://www.amazon.com/Quantum-Computing-since-Democritus-
Aar...](http://www.amazon.com/Quantum-Computing-since-Democritus-
Aaronson/dp/0521199565/ref=sr_1_1?ie=UTF8&qid=1436446995&sr=8-1&keywords=quantum+computing+since)

[2]:
[http://www.scottaaronson.com/democritus/](http://www.scottaaronson.com/democritus/)
, see "Lecture Notes" section.

~~~
ikeboy
>If you mean that he doesn't think "quantum" can solve NP-completeness, well,
of course he doesn't... he understands the mathematical proof that it doesn't,
so that's hardly surprising.

There's no proof BQP ≠ NP (as well as no proof it does).

Scott thinks it doesn't, but doesn't have a proof (if he did, he'd also have a
proof of P≠NP (and showing something implies a resolution of P versus NP is a
great proxy for "it's not easy and hasn't been solved yet")).

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ZoFreX
This article says nothing. It waffles vaguely about a number of unrelated
topics, adding nothing of value to anything that's been said previously, and
critically adding nothing of value to the paper it links to.

I suspect it is on the front page of Hacker News only because no-one else
wants to appear ignorant of the topics in question by pointing out that it
makes no sense.

~~~
mhurd
That's harsh but perhaps fair. My little blog post does represent a fair
amount of ignorance on my part and I too wonder why it got to the HN front
page.

I do appreciate the education I received :-)

------
crb002
No. Grab a copy of Ja Ja's book. There are some cool things you can do with a
PRAM machine. [http://www.amazon.com/Introduction-Parallel-Algorithms-
Josep...](http://www.amazon.com/Introduction-Parallel-Algorithms-Joseph-
JaJa/dp/0201548569)

