A Philosophical Argument for P != NP

David Levin sent me a link to a great blog post that talked about the question of whether P == NP.  From the post:

More often than I can remember, I've been asked some form of the following question: "If you computer scientists can't prove P=NP or P!=NP, then why aren't we justified in believing whichever one we want? And why is the 'consensus' that P!=NP anything more than a shared prejudice -- something you repeat to each other so your work won't seem irrelevant?"

The author then goes to offer 10 arguments for why it's overwhelmingly likely that P != NP.

I found the Philosophy Argument (#9) to be truly beautiful:

If P=NP, then the world would be a profoundly different place than we usually assume it to be. There would be no special value in "creative leaps," no fundamental gap between solving a problem and recognizing the solution once it's found. Everyone who could appreciate a symphony would be Mozart; everyone who could follow a step-by-step argument would be Gauss; everyone who could recognize a good investment strategy would be Warren Buffett. It's possible to put the point in Darwinian terms: if this is the sort of universe we inhabited, why wouldn't we already have evolved to take advantage of it? (Indeed, this is an argument not only for P != NP, but for NP-complete problems not being efficiently solvable in the physical world.)

It's beautiful for many reasons.  First, the analogy itself is beautiful.  Second, it's self-referential -- after reading it, I was struck by its elegance and surprised that I had never seen it in that way.  But, of course, that's the point -- it's very hard to formulate such an analogy, but it is comparatively easy to appreciate it.

Very nice indeed.


Posted Oct 31 2006, 10:46 AM by mike-vernal
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Comments

mikedb wrote re: A Philosophical Argument for P != NP
on 12-09-2006 7:44 AM
i don’t buy this argument.

if p=np is true, it may be only because the degree of the polynomial-time algorithm that solves the np-complete problems has an exponent of the order of magnitude 2**(2**m), where m = 1000! (say, just for the sake of argument).

then the polynomial time solution of any np-complete problem would be known to require no more than n**(2**(2**1000!)) steps, and so p=np would be true.

but I don’t know how much different the world would look to us if this were the case.

for example, i don’t think that if the above version of p=np were true, everyone would be a mozart or a gauss or a warren buffet, or that evolution would be much more expeditious than we’ve observed so far.

of course, once a sufficient amount of history has been accumulated, we might notice that we’d been solving np-complete problems significantly faster than we would have expected if p!=np were true.

even then, without a rigorous mathematical proof, we still wouldn’t know whether we were successful because p=np is true, or because, like warren buffet, we were just plain lucky.

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