Hi Steve, A few comments...
1) Nobody is trying to implement Hutter's AIXI design, it's a mathematical design intended as a "proof of principle" 2) Within Hutter's framework, one calculates the shortest program that explains the data, where "shortest" is measured on Turing machine M. Given a sufficient number of observations, the choice of M doesn't matter and AIXI will eventually learn any computable reward pattern. However, choosing the right M can greatly accelerate learning. In the case of a physical AGI system, choosing M to incorporate the correct laws of physics would obviously accelerate learning considerably. 3) Many AGI designs try to incorporate prior understanding of the structure & properties of the physical world, in various ways. I have a whole chapter on this in my forthcoming book on OpenCog.... E.g. OpenCog's design includes a physics-engine, which is used directly and to aid with inferential extrapolations... So I agree with most of your points, but I don't find them original except in phrasing ;) ... ben On Sun, Jun 27, 2010 at 2:30 PM, Steve Richfield <steve.richfi...@gmail.com>wrote: > Ben, et al, > > *I think I may finally grok the fundamental misdirection that current AGI > thinking has taken! > > *This is a bit subtle, and hence subject to misunderstanding. Therefore I > will first attempt to explain what I see, WITHOUT so much trying to convince > you (or anyone) that it is necessarily correct. Once I convey my vision, > then let the chips fall where they may. > > On Sun, Jun 27, 2010 at 6:35 AM, Ben Goertzel <b...@goertzel.org> wrote: > >> Hutter's AIXI for instance works [very roughly speaking] by choosing the >> most compact program that, based on historical data, would have yielded >> maximum reward >> > > ... and there it is! What did I see? > > Example applicable to the lengthy following discussion: > 1 - 2 > 2 - 2 > 3 - 2 > 4 - 2 > 5 - ? > What is "?". > > Now, I'll tell you that the left column represents the distance along a 4.5 > unit long table, and the right column represents the distance above the > floor that you will be as your walk the length of the table. Knowing this, > without ANY supporting physical experience, I would guess "?" to be zero, or > maybe a little more if I were to step off of the table and land onto > something lower, like the shoes that I left there. > > In an imaginary world where a GI boots up with a complete understanding of > physics, etc., we wouldn't prefer the simplest "program" at all, but rather > the simplest representation of the real world that is not physics/math *in > *consistent with our observations. All observations would be presumed to > be consistent with the response curves of our sensors, showing a world in > which Newton's laws prevail, etc. Armed with these presumptions, our > physics-complete AGI would look for the simplest set of *UN*observed > phenomena that explained the observed phenomena. This theory of a > physics-complete AGI seems undeniable, but of course, we are NOT born > physics-complete - or are we?! > > This all comes down to the limits of representational math. At great risk > of hand-waving on a keyboard, I'll try to explain by pseudo-translating the > concepts into NN/AGI terms. > > We all know about layering and columns in neural systems, and understand > Bayesian math. However, let's dig a little deeper into exactly what is being > represented by the "outputs" (or "terms" for died-in-the-wool AGIers). All > physical quantities are well known to have value, significance, and > dimensionality. Neurons/Terms (N/T) could easily be protein-tagged as to the > dimensionality that their functionality is capable of producing, so that > only compatible N/Ts could connect to them. However, let's dig a little > deeper into "dimensionality" > > Physicists think we live in an MKS (Meters, Kilograms, Seconds) world, and > that all dimensionality can be reduced to MKS. For physics purposes they may > be right (see challenge below), but maybe for information processing > purposes, they are missing some important things. > > *Challenge to MKS:* Note that some physicists and most astronomers utilize > "*dimensional analysis*" where they experimentally play with the > dimensions of observations to inductively find manipulations that would > yield the dimensions of unobservable quantities, e.g. the mass of a star, > and then run the numbers through the same manipulation to see if the results > at least have the right exponent. However, many/most such manipulations > produce nonsense, so they simply use this technique to jump from > observations to a list of prospective results with wildly different > exponents, and discard the results with the ridiculous exponents to find the > correct result. The frequent failures of this process indirectly > demonstrates that there is more to dimensionality (and hence physics) than > just MKS. Let's accept that, and presume that neurons must have already > dealt with whatever is missing from current thought. > > Consider, there is some (hopefully finite) set of reasonable manipulations > that could be done to Bayesian measures, with the various competing theories > of recognition representing part of that set. The reasonable mathematics to > perform on spacial features is probably different than the reasonable > mathematics to perform on recognized objects, or the recognition of > impossible observations, the manipulation of ideas, etc. Hence, N/Ts could > also be tagged for this deeper level of dimensionality, so that ideas don't > get mixed up with spacial features, etc. > > Note that we may not have perfected this process, and further, that this > process need not be perfected. Somewhere around the age of 12, many of our > neurons DIE. Perhaps these were just the victims of insufficiently precise > dimensional tagging? > > Once things can ONLY connect up in mathematically reasonable ways, what > remains between a newborn and a physics-complete AGI? Obviously, the > physics, which can be quite different on land than in the water. Hence, the > physics must also be learned. > > My point here is that if we impose a fragile requirement for mathematical > correctness against a developing system of physics and REJECT simplistic > explanations (not observations) that would violate either the mathematics or > the physics, then we don't end up with overly simplistic and useless > "programs", but rather we find more complex explanations that are physics > and mathematically believable. > > we should REJECT the concept of "pattern matching" UNLESS the discovered > pattern is both physics and mathematically correct. In short, the next > number in the "2, 2, 2, 2, ?" example sequence would *obviously* (by this > methodology) not be "2". > > OK, the BIG question here is whether a carefully-designed (or evolved over > 100 million years) system of representation can FORCE the construction of > systems (like us) that work this way, so that our "programs" aren't "simple" > at all, but rather are maximally correct? > > Anyway, I hope you grok the question above, and agree that the search for > the simplest "program" (without every possible reasonable physics and math > constraint that can be found) may be a considerable misdirection. Once you > impose physics and math constraints, which could potentially be done with > simplistic real-world mechanisms like protein tagging in neurons, the > problems then shifts to finding ANY solution that fits the complex > constraints, rather than finding the SIMPLEST solution without such > constraints. > > Once we can get past the questions, hopefully we can discuss prospective > answers. > > Are we in agreement here? > > Any thoughts? > > Steve > > *agi* | Archives <https://www.listbox.com/member/archive/303/=now> > <https://www.listbox.com/member/archive/rss/303/> | > Modify<https://www.listbox.com/member/?&;>Your Subscription > <http://www.listbox.com> > -- Ben Goertzel, PhD CEO, Novamente LLC and Biomind LLC CTO, Genescient Corp Vice Chairman, Humanity+ Advisor, Singularity University and Singularity Institute External Research Professor, Xiamen University, China b...@goertzel.org " “When nothing seems to help, I go look at a stonecutter hammering away at his rock, perhaps a hundred times without as much as a crack showing in it. Yet at the hundred and first blow it will split in two, and I know it was not that blow that did it, but all that had gone before.” ------------------------------------------- agi Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/ Modify Your Subscription: https://www.listbox.com/member/?member_id=8660244&id_secret=8660244-6e7fb59c Powered by Listbox: http://www.listbox.com
