CarlShulman comments on New report: Intelligence Explosion Microeconomics - Less Wrong

45 Post author: Eliezer_Yudkowsky 29 April 2013 11:14PM

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Comment author: CarlShulman 30 April 2013 10:46:22PM *  5 points [-]

ETA: this is a side point.

Here's Scott Aaronson describing people (university professors in computer science and cognitive science at RPI) who claim that the physical universe efficiently solves NP-hard problems:

It was only a matter of time before someone put the pieces together. Last summer Bringsjord and Taylor [24] posted a paper entitled “P=NP” to the arXiv. This paper argues that, since (1) finding a Steiner tree is NP-hard, (2) soap bubbles find a Steiner tree in polynomial time, (3) soap bubbles are classical objects, and (4) classical physics can be simulated by a Turing machine with polynomial slowdown, it follows that P = NP.

My immediate reaction was that the paper was a parody. However, a visit to Bringsjord’s home page2 suggested that it was not. Impelled, perhaps, by the same sort of curiosity that causes people to watch reality TV shows, I checked the discussion of this paper on the comp.theory newsgroup to see if anyone recognized the obvious error. And indeed, several posters pointed out that, although soap bubbles might reach a minimum-energy configuration with a small number of pegs, there is no “magical” reason why this should be true in general. By analogy, a rock in a mountain crevice could reach a lower-energy configuration by rolling up first and then down, but it is not observed to do so.

In other news, Bringsjord also claims to show by a modal argument, similar to the theistic modal argument (which he also endorses), that human brains are capable of hypercomputation: "it's possible humans are capable of hypercomputation, so they are capable of hypercomputation." For this reason he argues that superhumanly intelligent Turing machines/Von Neumann computers are impossible and belief in their possibility is fideistic.

Comment author: EHeller 30 April 2013 10:55:00PM *  6 points [-]

Here's Scott Aaronson describing people (university professors at RPI) who claim that the physical universe efficiently solves NP-hard problems.

This doesn't refute what you are responding to. Saying the universe can't solve a general NP problem in polynomial time is not the same thing as saying the universe cannot possibly solve specific instances of generally NP-complete problems, which is Tyrrell_McAllister's point, as far as I can parse. In general, the traveling salesman is NP-complete, however there are lots of cases where heuristics get the job done in polynomial time, even if those heuristics would run-away if they were given the wrong case.

To use Aaronson's soap bubbles, sometimes the soap bubble finds a Steiner tree, sometimes it doesn't. When it DOES, it has solved one instance of an NP-complete problem fairly quickly.