cousin_it comments on The prior of a hypothesis does not depend on its complexity - Less Wrong

26 Post author: cousin_it 26 August 2010 01:20PM

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Comment author: cousin_it 26 August 2010 02:42:34PM 0 points [-]

Not sure. I must've gone crazy for a minute there, thinking something like "being able to influence 3^^^^3 people is a huge conjunction of statements, thus low probability" - but of course the universal prior doesn't work like that. Struck that part.

Comment author: Manfred 02 January 2012 06:54:44AM 0 points [-]

It still seems relevant to me, since like in the "if my brother's wife's first son's best friend flips a coin, it will fall heads" example, the prior probability actually comes from opening up the statement and looking inside, in a way that would also differentiate just fine between stubbing 3 toes and stubbing 3^3^3 toes.

Comment author: Vladimir_Nesov 26 August 2010 03:05:12PM *  0 points [-]

Question: can we construct a low-complexity event that has universal prior much lower than is implied by its complexity, in other words it describes a relatively small set of programs, each of which has high complexity? Clearly it can't just describe one program, but maybe with a whole set of them it's possible. Naturally, the programs must be still hard-to-locate given the event.

Comment deleted 26 August 2010 03:09:50PM *  [-]
Comment author: Vladimir_Nesov 26 August 2010 03:13:33PM *  0 points [-]

K-complexity of the program defined by that criterion is about as low as that of the criterion, I'm afraid, so example 2 is invalid ("complexity" that is not K-complexity shouldn't be relevant). The universal prior for that theory is not astronomically low.

Edit: This is wrong, in particular because the criterion doesn't present an algorithm for finding the program, and because the program must by definition have high K-complexity.

Comment author: cousin_it 26 August 2010 03:22:28PM *  0 points [-]

Um, what? Can you exhibit a low-complexity algorithm that predicts sensory inputs in accordance with the theory from example 2? That's what it would mean for the universal prior to not be low. Or am I missing something?

Comment author: Vladimir_Nesov 26 August 2010 04:17:40PM *  0 points [-]

You are right, see updated comment.