gwern comments on Rationality Quotes May 2012 - Less Wrong

6 Post author: OpenThreadGuy 01 May 2012 11:37PM

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Comment author: RichardKennaway 08 May 2013 07:55:22AM 0 points [-]

Harder classes are subsets of NP-hard, and everything in NP-hard is hard enough to make the point.

Are you sure you want to make that claim? That all harder classes are subsets of NP-hard?

No, carelessness on my part. Doesn't affect my original point, that schemes for approximating Solomonoff or AIXI look like at least exponential brute force search.

You try to find a method that solves enough examples of the NP-hard problem well enough to sell the solutions, such that your more bounded ambition puts you back in the realm of P. This is done all the time -- freight scheduling software, for example. Or airline ticket price searching. Part of designing optimising compilers is not attempting analyses that take insanely long.

This is exactly the point made for computable approximations to AIXI.

Since AIXI is, by construction, the best possible intelligent agent, all work on AGI can, in a rather useless sense, be described as an approximation to AIXI. To the extent that such an attempt works (i.e. gets substantially further than past attempts at AGI), it will be because of new ideas not discovered by brute force search, not because it approximates AIXI.

Fantastic! I claim my extra 43 years of life.

43 years is a poor sort of immortality.

Comment author: gwern 08 May 2013 07:48:13PM 1 point [-]

schemes for approximating Solomonoff or AIXI look like at least exponential brute force search.

Well, yeah. Again - why would you expect anything else? Given that there exist problems which require that or worse for solution? How can a universal problem solver do any better?

Since AIXI is, by construction, the best possible intelligent agent, all work on AGI can, in a rather useless sense, be described as an approximation to AIXI.

Yes.

To the extent that such an attempt works (i.e. gets substantially further than past attempts at AGI), it will be because of new ideas not discovered by brute force search, not because it approximates AIXI.

No. Given how strange and different AIXI works, it can easily stimulate new ideas.

43 years is a poor sort of immortality.

It's more than I had before.

Comment author: RichardKennaway 09 May 2013 07:44:03AM 0 points [-]

No. Given how strange and different AIXI works, it can easily stimulate new ideas.

The spin-off argument. Here's a huge compendium of spinoffs of previous approaches to AGI. All very useful, but not AGI. I'm not expecting better from AIXI.

Comment author: gwern 09 May 2013 03:45:25PM 3 points [-]

Hm, so let's see; you started off mocking the impossibility and infeasibility of AIXI and any computable version:

I am not persuaded that the harder Bayesians have any more concrete answer. Solmonoff induction is uncomputable and seems to unnaturally favour short hypotheses involving Busy-Beaver-sized numbers. And any computable approximation to it looks to me like brute-forcing an NP-hard problem.

Then you admitted that actually every working solution can be seen as a form of SI/AIXI:

There might well be a theorem formalising that statement. There might also be one formalising the statement that every remotely optimal form of induction or decision-making is uncomputable. If that's the way it is, well, that's the way it is... Since AIXI is, by construction, the best possible intelligent agent, all work on AGI can, in a rather useless sense, be described as an approximation to AIXI

And now you're down to arguing that it'll be "very useful, but not AGI".

Well, I guess I can settle for that.

Comment author: RichardKennaway 10 May 2013 08:33:24AM -1 points [-]

I stand by the first quote. Every working solution can in a useless sense be seen as a form of SI/AIXI. The sense that a hot-air balloon can be seen as an approach to landing on the Moon.

And now you're down to arguing that it'll be "very useful, but not AGI".

At the very most. Whether AIXI-like algorithms get into the next edition of Russell and Norvig, having proved of practical value, well, history will decide that, and I'm not interested in predicting it. I will predict that it won't prove to be a viable approach to AGI.

Comment author: gwern 10 May 2013 04:30:54PM 0 points [-]

The sense that a hot-air balloon can be seen as an approach to landing on the Moon.

How can a hot air balloon even in theory be seen as that? Hot air has a specific limit, does it not - where its density equals the outside density?

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