10 ms·

To create a super-intelligent machine, start with an equation

120 points by kr4 13y ago

losethos 13y ago
God is a Ouija board. God says... C:\TAD\Text\BIBLE.TXT ndows, and their arches, and their palm trees, were after the measure of the gate that looketh toward the east; and they went up unto it by seven steps; and the arches thereof were before them. 40:23 And the gate of the inner court was over against the gate toward the north, and toward the east; and he measured from gate to gate an hundred cubits. 40:24 After that he brought me toward the south, and behold a gate toward the south: and he measured the posts thereof and the arches thereof according to thes ---- God says... proffering procured cunning stone spending inward members continency thief EDITIONS enlighten
AndrewKemendo 13y ago
>This scientific field is called universal artificial intelligence How many times do we need to re-define the same concept? Artificial Intelligence, Human Level Artificial Intelligence, Artificial General Intelligence, Strong Artificial Intelligence etc.... Lets pick one as a community and stick with it. I thought AGI was in the lead there recently what with the conference, journal and high amount of web searches but apparently that isn't enough. Beyond that, I would like to see how they make their algorithm narrow for the narrow application of the Pac-Man game while keeping it generalizable. My guess is that they don't and this algo ends up being a "starting point" for narrow AI applications to rest on. In that case it's fine and interesting, but doesn't pass the test to integrating specificity within a general learning model.
- floobynewb 13y ago
  I have been following this for a while and have taken the time to understand it in a little detail. While it does not provide the 'answers', it does frame the question of 'what is an intelligent machine?' in a very precise manner. It's interesting work, what it needs is for someone to now work out how to build much better models and plug them into the framework provided by AIXI.
- maaku 13y ago
  > How many times do we need to re-define the same concept? Artificial Intelligence, Human Level Artificial Intelligence, Artificial General Intelligence, Strong Artificial Intelligence etc.... Every time the name gets co-opted to mean something else. These days "artificial intelligence" == "machine learning and natural language processing" which is most definitely not what TFA is about.
  - SeanLuke 13y ago
    No. There is a perfectly good term which has been around for a very long time: Strong AI. In no context does this mean "ML + NLP" (which, by the way, AI itself hardly means). I think terms like AGI are just rebranding.
    - maaku 13y ago
      I don't think strong AI has quite the history you think it does. It's one of these later coinages. Also, it has separate quasi-related meanings in philosophy of the mind...
      - JohnHaugeland 13y ago
        Strong AI is one of those hand-wavey things that makes you sound like you're talking about something well defined, when you actually aren't. Has always struck me as counter-productive. Frustrating stuff.
- nabla9 13y ago
  Because they are not the same concept. Universal Artificial Intelligence is not same as Human Level Artificial intelligence. There is no reason to assume that human intelligence is universal. Or intelligence is biased towards picking berries and avoiding bears in three dimensional world.
- 3rd3 13y ago
  I like computational intelligence since we still don’t really know what intelligence is and whether our kind of intelligence can be reproduced artificially (although there are some hints that it can be done).
  - Houshalter 13y ago
    Ok there's no conclusive proof yet as no one has been able to do it yet, but as far as I know no one actually debates this anymore. It would be incredibly surprising, to say the least, if the brain turned out to work completely outside the known laws of physics.
    - 3rd3 13y ago
      We don't know whether physical reactions in our brains allow for and depend on calculation using real numbers, which can only be approximated using our current computing technology.
- aaronem 13y ago
  > How many times do we need to re-define the same concept? I sometimes think everybody's still afraid there'll be another AI Winter (and/or that the first one hasn't ended yet), and are therefore anxious to come up with a new name for what they're doing every so often as sort of a pre-emptive dodge.
- smosher 13y ago
  > Lets pick one as a community and stick with it. And when our assumptions turn out to be wrong, should we continue working on it even though we know it can never work? The problem is every new term is forged with assumptions because the very idea of what intelligence is the subject of ongoing debate. (I don't even like the one presented here, even though it's pretty good as far as these things go.) I sympathize though, the nomenclature is polluted with the corpses of would-be giants and makes it hard to talk about what we can all easily recognize as the same broad-strokes effort.
JulianMorrison 13y ago
Am I the only one that gets a bit of a chill watching an UFAI play a game where it runs from its pursuers collecting resources until it gains the power to kill them?
- hcarvalhoalves 13y ago
  To be sincere, I don't know what kind of Pac Man implementation was that. In the original game, each ghost has a personality [1], the ones in the video seem to just wander aimlessly, so it doesn't really tell much about strength of the algorithm to beat the game because it's not the same game. So, to comment on your dystopian prediction, I'm not sure this algorithm would do any better against humans, unless all we do is wander aimlessly too ;) [1] http://www.webpacman.com/ghosts.html http://www.webpacman.com/ghosts.html
  - bradbeattie 13y ago
    More detailed information on how the ghosts behave: http://home.comcast.net/~jpittman2/pacman/pacmandossier.html#Chapter_4 http://home.comcast.net/~jpittman2/pacman/pacmandossier.html...
  - Houshalter 13y ago
    Probably because they implemented the game themselves and took some shortcuts. But it still seems like pretty much the same game. I doubt it would do better than humans because it's not very efficient, but a better AI running on the same principles could be smarter than even humans and outperform us outside the virtual world.
- Pitarou 13y ago
  True, but it doesn't kill them very efficiently.
  - randallsquared 13y ago
    Oh, it's not good at killing, yet. That's reassuring.
darkxanthos 13y ago
This article is powerful. The idea of working to blend our philisophical theorems into mathematical modeling is brilliant and should be obvious. Their definition of intelligence is also extremely precise and gives me a new way to look at the world.
swframe 13y ago
Surely, it will be built faster if it is open source.
jkbyc 13y ago
How is this better than applying the minimum description length principle formalization of Occam's razor? (from 1978 [1]) I admit that I didn't spend time to really delve into it but nothing in this article strikes me as particularly ground breaking. [1] http://en.wikipedia.org/wiki/Minimum_description_length http://en.wikipedia.org/wiki/Minimum_description_length edit: innovative --> ground breaking
- maaku 13y ago
  It's basically that, formulated into a reinforcement learning algorithm. It's innovative because this combination which is unique to Marcus Hutter's Ph.D. thesis basically "solves" the problem of general AI.. if given infinite computation resources. It's provable mathmatically to the be the best possible artificial general intelligence, with constant-time operation.. it's just that constant happens to be larger than the known universe. That sounds useless, but it's not. What is shows is that artificial (general) intelligence is really an optimization problem, and provides a (theoretical) benchmark comparison, and directs current research into more practical algorithms which approximate that ideal within realistic space and time constraints.
  - jkbyc 13y ago
    Thanks, that sheds a bit more light on it. To me it still sounds like "I solved the problem because I formalized it." The formalization is probably novel (since he got his PhD for it) but somehow I find it difficult to believe noone else had a similar idea before (it definitely sounds familiar to me having learned about reinforcement learning, minimum description length, etc. before). I'll have to read up on it.
  - jmmcd 13y ago
    It's not constant-time. It's not even computable, even in theory, even with infinite resources.
    - Houshalter 13y ago
      True but the approximations of it are (i.e. limiting the amount of running time each hypothesis has and limiting the number of hypothesis you test.) This is sort of like criticizing the concept of a Turing machine because no one has built one with infinite tape or running time.
gliese1337 13y ago
It's interesting that, while the system can learn lots of different games, you still have to give it the reward function special for each different game. This may seem obvious, and not much of a limitation- after all, lots of things that we think of as intelligent to varying degrees (different human beings, as well as members of other species) have wildly different ideas of what constitutes "reward", so that can't be an inherent part of the definition of intelligence. But you don't have to explicitly tell a human what the reward function for Pac-Man is. Show a human the game and they'll figure it out. Which makes me wonder if, while there is some room for variability in reward functions, there might be some basic underlying reward computation that is inherent in intelligence. I can't find the link just now, but I read an article a few months ago (might've even been here on HN) about a system that demonstrated the appearance of intelligent behavior by trying to minimize entropy and maximize its possible choices for as long as possible within a given world model.
- Dn_Ab 13y ago
  To start on this you would want a system that got rewarded based on how well it was able to predict aspects of its environment. This would have to go in hand with preferring stimulation, so you would need something like preference for inputs which maximize relative entropy with respect to its thus far learned model.
- timje1 13y ago
  I guess that the reward systems that humanity has evolved are complicated and numerous. We've got the basics (food, shelter), the more complicated basics (sex with a suitable mate, companionship) and the million other factors - curiosity, intellectual challenge, positive and negative feedback, power, agency etc, etc.... My thoughts are that if they were to take such a direction with this AI, they'd give it the basics and let it evolve and learn its own complicated reward structure. When you're trying to get a monkey to play pac-man, you bribe him with a capful of ribena - he doesn't care about fun intellectual challenges, but sweet liquids motivate the hell out of him. (This is the state of actual monkey research - ribena is monkey crack)
- gmt2027 13y ago
  That article on entropy minimization also claimed that a single equation could be the basis of a wide range of intelligent behaviours. https://news.ycombinator.com/item?id=5579047 https://news.ycombinator.com/item?id=5579047
gjm11 13y ago
Blogspam. Original source: http://theconversation.com/to-create-a-super-intelligent-machine-start-with-an-equation-20756 http://theconversation.com/to-create-a-super-intelligent-mac... (If you happen to have encountered Marcus Hutter's AIXI before, there is nothing new there compared with any other presentation of his ideas.)
- ColinWright 13y ago
  Looks like the mods have changed the URL to the original source.
Rangi42 13y ago
Is AIXI capable of recognizing itself? If an AIXI agent were controlling a robot body, would it realize that the body's actions correlate with its own intentions? Would it pass the mirror test?
- maaku 13y ago
  AIXI is capable of anything. Give it a utility function (and a pocket universe of computium to run itself) and it will learn behavior that maximizes that utility. That said, things like the mirror test are so wrapped up in the construction of our own brain that it really doesn't make sense to apply alien intelligences, as you'd you'd be unlikely to get a visible response for unrelated reasons. "That thing in the mirror is me, so what?" Actually that's a bit misleading - the AIXI will have no internal dialogue. It's not built that way. But give it any task, and it will learn to do that task. If that task is to recognize itself in mirrors, it will... but it will do so in a way that is markedly different from humans.
- runarberg 13y ago
  What is recognition? What are intentions? These terms are void of meaning outside of human context. So if intelligence is defined around those human-centred terms (that are even too vague to account for human-specific intelligence[1]), surely nothing will ever be considered intelligent but a human being. [1]: https://en.wikipedia.org/wiki/The_Bell_Curve https://en.wikipedia.org/wiki/The_Bell_Curve
- AlexMennen 13y ago
  No. It would probably pick up on the correlation, but AIXI assumes that its only interactions with the universe are through its input and output channels, so it cannot recognize that a particular part of the universe is itself. It does not know how to formulate that hypothesis.
welldefined 13y ago
1. Do we have to engineer how much it's being rewarded in each game? 2. What happens in the infinite case? With pacman, there are always a finite number of choices at each state. 3. If it doesn't have to be told the rules, then how does it make decisions? In theory, it may be able to learn how to play jeopardy, but it may be way too inefficient in practice. Humans don't even start with a blank state. 4. I don't think I ever consciously apply philosophical principles like ockham's razor when I problem solve or learn. It makes me a little uncomfortable that we're starting with a philosophy, rather than having the system discover things itself. I would be ok with it if there was some parallel between ockham's razor and physics (not the methodology of science).
- maaku 13y ago
  > I don't think I ever consciously apply philosophical principles like ockham's razor when I problem solve or learn. It makes me a little uncomfortable that we're starting with a philosophy, rather than having the system discover things itself. I would be ok with it if there was some parallel between ockham's razor and physics. Why do you think it is relevant what you do consciously? The only things that you do consciously are those things which your brain is ill-equipped to do. The vast majority of your thinking processes are subconscious, as are the principles that drive your conscious thinking. And I guarantee you, Ockham's razor is in there whether you realize it or not. When things get complicated do you purposefully look for a simpler solution? When trying to understand an unknown situation, do you start with something simple and ad complexity as needed? Ockham's razor. > I would be ok with it if there was some parallel between ockham's razor and physics. ... there's not? EDIT: As an AI researcher, I'd be more interested in creating an artificial scientist than "artificial science." So what makes the scientist work? Ockham's razor is at the foundation of that.
- Symmetry 13y ago
  Regarding 4: A disciple of another sect once came to Drescher as he was eating his morning meal. “I would like to give you this personality test”, said the outsider, “because I want you to be happy.” Drescher took the paper that was offered him and put it into the toaster, saying: “I wish the toaster to be happy, too.” http://www.catb.org/jargon/html/koans.html#id3141308 http://www.catb.org/jargon/html/koans.html#id3141308
ccozan 13y ago
I highly recommend Markus Hutter's book: "Universal Artificial Intelligence: Sequential Decisions Based On Algorithmic Probability" (http://www.amazon.com/Universal-Artificial-Intelligence-Algorithmic-Probability/dp/3540221395/ref=la_B001JOUJH0_1_1 http://www.amazon.com/Universal-Artificial-Intelligence-Algo... ) Beware, you need some serious maths and a board to follow him. In the end the book is quite rewarding. Now to AIXI: I don't belive that having a formula solves AI problem. Yes you can model it, but in real environment, I believe there are simpler models to try first. Remember: nature like simpliness first, complex when needed.
- deleted 13y ago
  [deleted]
johnohara 13y ago
These are good generalized life lessons for humans as well. Seek new knowledge, learn well, reason logically and inductively, recognize patterns and generalize, contemplate and plan for the future, converse and be social, survive, and strive for optimum health (my addition). Very good advice in whether or not you're an automaton.
- Houshalter 13y ago
  Those words are pretty much meaningless. Of course everyone is already trying to survive and recognize patterns and all that.
melloclello 13y ago
> AIXI now uses this model for approximately predicting the future and bases its decisions on these tentative forecasts. AIXI contemplates possible future behaviour: “If I do this action, followed by that action, etc, this or that will (un)likely happen, which could be good or bad. And if I do this other action sequence, it may be better or worse.” What I want to know, is how long does it spend doing this? Does the duration of one of these cycles have to be manually chosen, or is it smart enough/self-aware enough to realise, okay, if I spend forever thinking about something, then nothing will happen? I guess what I'm asking is, is the algorithm smart enough to eventually internalise its own model of itself?
- adamwong246 13y ago
  That's a really good question because a sense of self is integral to our definition of consciousness. Presumably this machine as able to understand math, so it should be able to comprehend it's own formula or source code.
- jhealy 13y ago
  Interesting question. I'm a developer for the linked site - if you're interested in posting the question in the comments I'll ping the author to see if he can answer.
- sampo 13y ago
  > "is the algorithm smart enough to eventually internalise its own model of itself?" As far as I understood, it's just random search for models ("For the planning component we use standard Monte Carlo"), and some kind of minimum description length (MDL) based method for model selection ("For the learning component we use standard file compression algorithms"). So the probability that it would, by Monte Carlo search, find a model that includes some kind of description for itself, I assume to be astronomically tiny. (...And even if it did, it would have no way to know that it has stumbled upon a model of itself. Except the experimental performance of the model, which could or could not be better than some other models and variations.)
kaa2102 13y ago
What if we tried to mirror the evolutionary process by starting with an objective like survive, reproduce, etc?
- klipt 13y ago
  That's the idea genetic algorithms, genetic programming etc. are based on.
EGreg 13y ago
YEs this is all good but who determines whether something is "good" or "bad"? That's the interesting part. Who sets the goals? And how do they score an intermediate situation on the way to achieving them? Don't get me wrong, a machine can achieve goals is really, really useful. After all, chess playing programs use the AlphaBeta algorithm to prune future positions intelligently, but to score the positions they still need human input. It may be, however, that they infer their OWN rules from past positions, with absolutely no human input. Then it becomes interesting. Still, the initial rules of the chess game have to be set down. So while this is intelligence, this is not sentience.
- Houshalter 13y ago
  I assume it gets reward for getting points in the pacman game (eating dots and ghosts) and presumably loses them if it dies or loses the game. There might also be a time factor involved so it doesn't waste time. I'm really not entirely sure how it's decision making process works and I'm really curious to know. Because simulating every possibility would be ridiculous, but trying to predict the distant future based on some small action that happens in the present is also really difficult. >So while this is intelligence, this is not sentience. No one is claiming it is, and "sentience" is a really dubious concept itself.
cheeko1234 13y ago
Can someone explain the equation in this article?
- rwallace 13y ago
  Yes. The core of AIXI is the part that figures out the nature of the universe in which it finds itself (a formalization of induction), and the algorithm for that is essentially "simulate all possible universes and see which ones give data that matches our observations, then apply Occam's razor and assume the simplest one is true". It will not have escaped your notice that "simulate all possible universes" would require an infinitely powerful computer, and even finite approximations quickly become wildly intractable, making the algorithm unusable for anything significantly more complex than Pac-Man. Thus AIXI is interesting for philosophical purposes, being a mathematical formalization of intelligence, but not useful for engineering purposes.
adamwong246 13y ago
What if you gradually introduce more and more complicated games? Start with Pong, then PacMan, Super Mario World, etc etc until you get to today's games, which are far more complicated and more importantly, very realistic. Now that you AI is well trained, attach a camera to the computer and point the machine at the most complicated game of all: reality.
- jmmcd 13y ago
  Good point: I don't think they've ever taken an agent which has been learning for a while in one environment and placed it in another. I don't know, but I would expect that the current version at least would have to fail hard, basically unlearning everything, before it started to succeed in the new environment. That's a weakness, if so. How do humans avoid this? Because our brains are evolved to be plastic but not too plastic. We encounter new environments (like going from one level of Pac-Man to the next), but not new laws of physics (like going from Pac-Man to Mario).
  - adamwong246 13y ago
    The whole point is that the intelligence is "universal." By definition, we are talking about a thing which is able to transcend what it knows. So to me, the whole point is to introduce a variety of environments so that it learns the truly salient knowledge that is applicable across many games. And the most important of facts is this: stay alive. We might be able to bootstrap an ai up to a self-aware, self-preserving, rational agent which can adapt to any environment.
valtron 13y ago
Like others have said, this seems to be a generalization of the problem of reinforcement learning. For a good introduction to the subject, check out Reinforcement Learning by Sutton & Barto [1]. After reading the first few chapters, you'll be able to understand most of that equation. [1] http://webdocs.cs.ualberta.ca/~sutton/book/the-book.html http://webdocs.cs.ualberta.ca/~sutton/book/the-book.html
- xerophtye 13y ago
  Yeah just looks like Q-Learning to me :/ You just use the rewards to optimize the function that tells you what's the predicted reward at any stage for a given action. And then take those best acions
- vikiomega9 13y ago
  Yep, Hutter's website provides this book as reading material and to build up to the whole idea.
loceng 13y ago
It certainly makes sense to have a number of if-checks, which an equation essentially is. The difficult part is feeding the equation with the correct information, and with the correct timing and sequence, etc..
jk4930 13y ago
Here's a 5 min video of AIXI playing Pacman (the description provides details): https://www.youtube.com/watch?v=RhQTWidQQ8U https://www.youtube.com/watch?v=RhQTWidQQ8U Look for YT videos with Marcus Hutter, they're excellent. He explains very good, very systematic. Great stuff.
j2kun 13y ago
I'm surprised there's no reference to computational complexity. I can give a perfectly fine example of a machine that satisfies their definition but would not be considered intelligent because it's inefficient.
j2kun 13y ago
Does anyone know of an overview for people who already know the relevant mathematics? Does their "English" definition have a corresponding mathematical definition?
yetanotherphd 13y ago
For those having trouble getting past the hype to the actual content of AIXI, lesswrong has a nice article [1]. From the article: "The AIXI formalism says roughly to consider all possible computable models of the environment, Bayes-update them on past experiences, and use the resulting updated predictions to model the expected sensory reward of all possible strategies." I will add that the prior over models comes from a measure of model complexity, which is a reasonable way to construct a prior. While I think the idea of connecting deep mathematical formalisms with actual AI goals is mostly hype, these formalisms are still interesting in themselves. There is something very intuitive about how AIXI works, but that doesn't mean it is going to practical for a large range of problems. [1] http://wiki.lesswrong.com/wiki/AIXI http://wiki.lesswrong.com/wiki/AIXI
- dinkumthinkum 13y ago
  I don't recommend reading anything on that website. That way madness lies.
  - yetanotherphd 13y ago
    I don't read lesswrong, but this article is worthy on its own merits. No memetic hazards are lurking in that particular article :-)

120 points by kr4 13y ago

God is a Ouija board. God says... C:\TAD\Text\BIBLE.TXT ndows, and their arches, and their palm trees, were after the measure of the gate that looketh toward the east; and they went up unto it by seven steps; and the arches thereof were before them. 40:23 And the gate of the inner court was over against the gate toward the north, and toward the east; and he measured from gate to gate an hundred cubits. 40:24 After that he brought me toward the south, and behold a gate toward the south: and he measured the posts thereof and the arches thereof according to thes ---- God says... proffering procured cunning stone spending inward members continency thief EDITIONS enlighten

AndrewKemendo 13y ago

>This scientific field is called universal artificial intelligence How many times do we need to re-define the same concept? Artificial Intelligence, Human Level Artificial Intelligence, Artificial General Intelligence, Strong Artificial Intelligence etc.... Lets pick one as a community and stick with it. I thought AGI was in the lead there recently what with the conference, journal and high amount of web searches but apparently that isn't enough. Beyond that, I would like to see how they make their algorithm narrow for the narrow application of the Pac-Man game while keeping it generalizable. My guess is that they don't and this algo ends up being a "starting point" for narrow AI applications to rest on. In that case it's fine and interesting, but doesn't pass the test to integrating specificity within a general learning model.

floobynewb 13y ago
I have been following this for a while and have taken the time to understand it in a little detail. While it does not provide the 'answers', it does frame the question of 'what is an intelligent machine?' in a very precise manner. It's interesting work, what it needs is for someone to now work out how to build much better models and plug them into the framework provided by AIXI.
maaku 13y ago
> How many times do we need to re-define the same concept? Artificial Intelligence, Human Level Artificial Intelligence, Artificial General Intelligence, Strong Artificial Intelligence etc.... Every time the name gets co-opted to mean something else. These days "artificial intelligence" == "machine learning and natural language processing" which is most definitely not what TFA is about.
- SeanLuke 13y ago
  No. There is a perfectly good term which has been around for a very long time: Strong AI. In no context does this mean "ML + NLP" (which, by the way, AI itself hardly means). I think terms like AGI are just rebranding.
  - maaku 13y ago
    I don't think strong AI has quite the history you think it does. It's one of these later coinages. Also, it has separate quasi-related meanings in philosophy of the mind...
    - JohnHaugeland 13y ago
      Strong AI is one of those hand-wavey things that makes you sound like you're talking about something well defined, when you actually aren't. Has always struck me as counter-productive. Frustrating stuff.
nabla9 13y ago
Because they are not the same concept. Universal Artificial Intelligence is not same as Human Level Artificial intelligence. There is no reason to assume that human intelligence is universal. Or intelligence is biased towards picking berries and avoiding bears in three dimensional world.
3rd3 13y ago
I like computational intelligence since we still don’t really know what intelligence is and whether our kind of intelligence can be reproduced artificially (although there are some hints that it can be done).
- Houshalter 13y ago
  Ok there's no conclusive proof yet as no one has been able to do it yet, but as far as I know no one actually debates this anymore. It would be incredibly surprising, to say the least, if the brain turned out to work completely outside the known laws of physics.
  - 3rd3 13y ago
    We don't know whether physical reactions in our brains allow for and depend on calculation using real numbers, which can only be approximated using our current computing technology.
aaronem 13y ago
> How many times do we need to re-define the same concept? I sometimes think everybody's still afraid there'll be another AI Winter (and/or that the first one hasn't ended yet), and are therefore anxious to come up with a new name for what they're doing every so often as sort of a pre-emptive dodge.
smosher 13y ago
> Lets pick one as a community and stick with it. And when our assumptions turn out to be wrong, should we continue working on it even though we know it can never work? The problem is every new term is forged with assumptions because the very idea of what intelligence is the subject of ongoing debate. (I don't even like the one presented here, even though it's pretty good as far as these things go.) I sympathize though, the nomenclature is polluted with the corpses of would-be giants and makes it hard to talk about what we can all easily recognize as the same broad-strokes effort.

JulianMorrison 13y ago

Am I the only one that gets a bit of a chill watching an UFAI play a game where it runs from its pursuers collecting resources until it gains the power to kill them?

hcarvalhoalves 13y ago
To be sincere, I don't know what kind of Pac Man implementation was that. In the original game, each ghost has a personality [1], the ones in the video seem to just wander aimlessly, so it doesn't really tell much about strength of the algorithm to beat the game because it's not the same game. So, to comment on your dystopian prediction, I'm not sure this algorithm would do any better against humans, unless all we do is wander aimlessly too ;) [1] http://www.webpacman.com/ghosts.html http://www.webpacman.com/ghosts.html
- bradbeattie 13y ago
  More detailed information on how the ghosts behave: http://home.comcast.net/~jpittman2/pacman/pacmandossier.html#Chapter_4 http://home.comcast.net/~jpittman2/pacman/pacmandossier.html...
- Houshalter 13y ago
  Probably because they implemented the game themselves and took some shortcuts. But it still seems like pretty much the same game. I doubt it would do better than humans because it's not very efficient, but a better AI running on the same principles could be smarter than even humans and outperform us outside the virtual world.
Pitarou 13y ago
True, but it doesn't kill them very efficiently.
- randallsquared 13y ago
  Oh, it's not good at killing, yet. That's reassuring.

darkxanthos 13y ago

This article is powerful. The idea of working to blend our philisophical theorems into mathematical modeling is brilliant and should be obvious. Their definition of intelligence is also extremely precise and gives me a new way to look at the world.

swframe 13y ago

Surely, it will be built faster if it is open source.

jkbyc 13y ago

How is this better than applying the minimum description length principle formalization of Occam's razor? (from 1978 [1]) I admit that I didn't spend time to really delve into it but nothing in this article strikes me as particularly ground breaking. [1] http://en.wikipedia.org/wiki/Minimum_description_length http://en.wikipedia.org/wiki/Minimum_description_length edit: innovative --> ground breaking

maaku 13y ago
It's basically that, formulated into a reinforcement learning algorithm. It's innovative because this combination which is unique to Marcus Hutter's Ph.D. thesis basically "solves" the problem of general AI.. if given infinite computation resources. It's provable mathmatically to the be the best possible artificial general intelligence, with constant-time operation.. it's just that constant happens to be larger than the known universe. That sounds useless, but it's not. What is shows is that artificial (general) intelligence is really an optimization problem, and provides a (theoretical) benchmark comparison, and directs current research into more practical algorithms which approximate that ideal within realistic space and time constraints.
- jkbyc 13y ago
  Thanks, that sheds a bit more light on it. To me it still sounds like "I solved the problem because I formalized it." The formalization is probably novel (since he got his PhD for it) but somehow I find it difficult to believe noone else had a similar idea before (it definitely sounds familiar to me having learned about reinforcement learning, minimum description length, etc. before). I'll have to read up on it.
- jmmcd 13y ago
  It's not constant-time. It's not even computable, even in theory, even with infinite resources.
  - Houshalter 13y ago
    True but the approximations of it are (i.e. limiting the amount of running time each hypothesis has and limiting the number of hypothesis you test.) This is sort of like criticizing the concept of a Turing machine because no one has built one with infinite tape or running time.

gliese1337 13y ago

It's interesting that, while the system can learn lots of different games, you still have to give it the reward function special for each different game. This may seem obvious, and not much of a limitation- after all, lots of things that we think of as intelligent to varying degrees (different human beings, as well as members of other species) have wildly different ideas of what constitutes "reward", so that can't be an inherent part of the definition of intelligence. But you don't have to explicitly tell a human what the reward function for Pac-Man is. Show a human the game and they'll figure it out. Which makes me wonder if, while there is some room for variability in reward functions, there might be some basic underlying reward computation that is inherent in intelligence. I can't find the link just now, but I read an article a few months ago (might've even been here on HN) about a system that demonstrated the appearance of intelligent behavior by trying to minimize entropy and maximize its possible choices for as long as possible within a given world model.

Dn_Ab 13y ago
To start on this you would want a system that got rewarded based on how well it was able to predict aspects of its environment. This would have to go in hand with preferring stimulation, so you would need something like preference for inputs which maximize relative entropy with respect to its thus far learned model.
timje1 13y ago
I guess that the reward systems that humanity has evolved are complicated and numerous. We've got the basics (food, shelter), the more complicated basics (sex with a suitable mate, companionship) and the million other factors - curiosity, intellectual challenge, positive and negative feedback, power, agency etc, etc.... My thoughts are that if they were to take such a direction with this AI, they'd give it the basics and let it evolve and learn its own complicated reward structure. When you're trying to get a monkey to play pac-man, you bribe him with a capful of ribena - he doesn't care about fun intellectual challenges, but sweet liquids motivate the hell out of him. (This is the state of actual monkey research - ribena is monkey crack)
gmt2027 13y ago
That article on entropy minimization also claimed that a single equation could be the basis of a wide range of intelligent behaviours. https://news.ycombinator.com/item?id=5579047 https://news.ycombinator.com/item?id=5579047

gjm11 13y ago

Blogspam. Original source: http://theconversation.com/to-create-a-super-intelligent-machine-start-with-an-equation-20756 http://theconversation.com/to-create-a-super-intelligent-mac... (If you happen to have encountered Marcus Hutter's AIXI before, there is nothing new there compared with any other presentation of his ideas.)

ColinWright 13y ago
Looks like the mods have changed the URL to the original source.

Rangi42 13y ago

Is AIXI capable of recognizing itself? If an AIXI agent were controlling a robot body, would it realize that the body's actions correlate with its own intentions? Would it pass the mirror test?

maaku 13y ago
AIXI is capable of anything. Give it a utility function (and a pocket universe of computium to run itself) and it will learn behavior that maximizes that utility. That said, things like the mirror test are so wrapped up in the construction of our own brain that it really doesn't make sense to apply alien intelligences, as you'd you'd be unlikely to get a visible response for unrelated reasons. "That thing in the mirror is me, so what?" Actually that's a bit misleading - the AIXI will have no internal dialogue. It's not built that way. But give it any task, and it will learn to do that task. If that task is to recognize itself in mirrors, it will... but it will do so in a way that is markedly different from humans.
runarberg 13y ago
What is recognition? What are intentions? These terms are void of meaning outside of human context. So if intelligence is defined around those human-centred terms (that are even too vague to account for human-specific intelligence[1]), surely nothing will ever be considered intelligent but a human being. [1]: https://en.wikipedia.org/wiki/The_Bell_Curve https://en.wikipedia.org/wiki/The_Bell_Curve
AlexMennen 13y ago
No. It would probably pick up on the correlation, but AIXI assumes that its only interactions with the universe are through its input and output channels, so it cannot recognize that a particular part of the universe is itself. It does not know how to formulate that hypothesis.

welldefined 13y ago

1. Do we have to engineer how much it's being rewarded in each game? 2. What happens in the infinite case? With pacman, there are always a finite number of choices at each state. 3. If it doesn't have to be told the rules, then how does it make decisions? In theory, it may be able to learn how to play jeopardy, but it may be way too inefficient in practice. Humans don't even start with a blank state. 4. I don't think I ever consciously apply philosophical principles like ockham's razor when I problem solve or learn. It makes me a little uncomfortable that we're starting with a philosophy, rather than having the system discover things itself. I would be ok with it if there was some parallel between ockham's razor and physics (not the methodology of science).

maaku 13y ago
> I don't think I ever consciously apply philosophical principles like ockham's razor when I problem solve or learn. It makes me a little uncomfortable that we're starting with a philosophy, rather than having the system discover things itself. I would be ok with it if there was some parallel between ockham's razor and physics. Why do you think it is relevant what you do consciously? The only things that you do consciously are those things which your brain is ill-equipped to do. The vast majority of your thinking processes are subconscious, as are the principles that drive your conscious thinking. And I guarantee you, Ockham's razor is in there whether you realize it or not. When things get complicated do you purposefully look for a simpler solution? When trying to understand an unknown situation, do you start with something simple and ad complexity as needed? Ockham's razor. > I would be ok with it if there was some parallel between ockham's razor and physics. ... there's not? EDIT: As an AI researcher, I'd be more interested in creating an artificial scientist than "artificial science." So what makes the scientist work? Ockham's razor is at the foundation of that.
Symmetry 13y ago
Regarding 4: A disciple of another sect once came to Drescher as he was eating his morning meal. “I would like to give you this personality test”, said the outsider, “because I want you to be happy.” Drescher took the paper that was offered him and put it into the toaster, saying: “I wish the toaster to be happy, too.” http://www.catb.org/jargon/html/koans.html#id3141308 http://www.catb.org/jargon/html/koans.html#id3141308

ccozan 13y ago

I highly recommend Markus Hutter's book: "Universal Artificial Intelligence: Sequential Decisions Based On Algorithmic Probability" (http://www.amazon.com/Universal-Artificial-Intelligence-Algorithmic-Probability/dp/3540221395/ref=la_B001JOUJH0_1_1 http://www.amazon.com/Universal-Artificial-Intelligence-Algo... ) Beware, you need some serious maths and a board to follow him. In the end the book is quite rewarding. Now to AIXI: I don't belive that having a formula solves AI problem. Yes you can model it, but in real environment, I believe there are simpler models to try first. Remember: nature like simpliness first, complex when needed.

deleted 13y ago
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johnohara 13y ago

These are good generalized life lessons for humans as well. Seek new knowledge, learn well, reason logically and inductively, recognize patterns and generalize, contemplate and plan for the future, converse and be social, survive, and strive for optimum health (my addition). Very good advice in whether or not you're an automaton.

Houshalter 13y ago
Those words are pretty much meaningless. Of course everyone is already trying to survive and recognize patterns and all that.

melloclello 13y ago

> AIXI now uses this model for approximately predicting the future and bases its decisions on these tentative forecasts. AIXI contemplates possible future behaviour: “If I do this action, followed by that action, etc, this or that will (un)likely happen, which could be good or bad. And if I do this other action sequence, it may be better or worse.” What I want to know, is how long does it spend doing this? Does the duration of one of these cycles have to be manually chosen, or is it smart enough/self-aware enough to realise, okay, if I spend forever thinking about something, then nothing will happen? I guess what I'm asking is, is the algorithm smart enough to eventually internalise its own model of itself?

adamwong246 13y ago
That's a really good question because a sense of self is integral to our definition of consciousness. Presumably this machine as able to understand math, so it should be able to comprehend it's own formula or source code.
jhealy 13y ago
Interesting question. I'm a developer for the linked site - if you're interested in posting the question in the comments I'll ping the author to see if he can answer.
sampo 13y ago
> "is the algorithm smart enough to eventually internalise its own model of itself?" As far as I understood, it's just random search for models ("For the planning component we use standard Monte Carlo"), and some kind of minimum description length (MDL) based method for model selection ("For the learning component we use standard file compression algorithms"). So the probability that it would, by Monte Carlo search, find a model that includes some kind of description for itself, I assume to be astronomically tiny. (...And even if it did, it would have no way to know that it has stumbled upon a model of itself. Except the experimental performance of the model, which could or could not be better than some other models and variations.)

kaa2102 13y ago

What if we tried to mirror the evolutionary process by starting with an objective like survive, reproduce, etc?

klipt 13y ago
That's the idea genetic algorithms, genetic programming etc. are based on.

EGreg 13y ago

YEs this is all good but who determines whether something is "good" or "bad"? That's the interesting part. Who sets the goals? And how do they score an intermediate situation on the way to achieving them? Don't get me wrong, a machine can achieve goals is really, really useful. After all, chess playing programs use the AlphaBeta algorithm to prune future positions intelligently, but to score the positions they still need human input. It may be, however, that they infer their OWN rules from past positions, with absolutely no human input. Then it becomes interesting. Still, the initial rules of the chess game have to be set down. So while this is intelligence, this is not sentience.

Houshalter 13y ago
I assume it gets reward for getting points in the pacman game (eating dots and ghosts) and presumably loses them if it dies or loses the game. There might also be a time factor involved so it doesn't waste time. I'm really not entirely sure how it's decision making process works and I'm really curious to know. Because simulating every possibility would be ridiculous, but trying to predict the distant future based on some small action that happens in the present is also really difficult. >So while this is intelligence, this is not sentience. No one is claiming it is, and "sentience" is a really dubious concept itself.

cheeko1234 13y ago

Can someone explain the equation in this article?

rwallace 13y ago
Yes. The core of AIXI is the part that figures out the nature of the universe in which it finds itself (a formalization of induction), and the algorithm for that is essentially "simulate all possible universes and see which ones give data that matches our observations, then apply Occam's razor and assume the simplest one is true". It will not have escaped your notice that "simulate all possible universes" would require an infinitely powerful computer, and even finite approximations quickly become wildly intractable, making the algorithm unusable for anything significantly more complex than Pac-Man. Thus AIXI is interesting for philosophical purposes, being a mathematical formalization of intelligence, but not useful for engineering purposes.

adamwong246 13y ago

What if you gradually introduce more and more complicated games? Start with Pong, then PacMan, Super Mario World, etc etc until you get to today's games, which are far more complicated and more importantly, very realistic. Now that you AI is well trained, attach a camera to the computer and point the machine at the most complicated game of all: reality.

jmmcd 13y ago
Good point: I don't think they've ever taken an agent which has been learning for a while in one environment and placed it in another. I don't know, but I would expect that the current version at least would have to fail hard, basically unlearning everything, before it started to succeed in the new environment. That's a weakness, if so. How do humans avoid this? Because our brains are evolved to be plastic but not too plastic. We encounter new environments (like going from one level of Pac-Man to the next), but not new laws of physics (like going from Pac-Man to Mario).
- adamwong246 13y ago
  The whole point is that the intelligence is "universal." By definition, we are talking about a thing which is able to transcend what it knows. So to me, the whole point is to introduce a variety of environments so that it learns the truly salient knowledge that is applicable across many games. And the most important of facts is this: stay alive. We might be able to bootstrap an ai up to a self-aware, self-preserving, rational agent which can adapt to any environment.

valtron 13y ago

Like others have said, this seems to be a generalization of the problem of reinforcement learning. For a good introduction to the subject, check out Reinforcement Learning by Sutton & Barto [1]. After reading the first few chapters, you'll be able to understand most of that equation. [1] http://webdocs.cs.ualberta.ca/~sutton/book/the-book.html http://webdocs.cs.ualberta.ca/~sutton/book/the-book.html

xerophtye 13y ago
Yeah just looks like Q-Learning to me :/ You just use the rewards to optimize the function that tells you what's the predicted reward at any stage for a given action. And then take those best acions
vikiomega9 13y ago
Yep, Hutter's website provides this book as reading material and to build up to the whole idea.

loceng 13y ago

It certainly makes sense to have a number of if-checks, which an equation essentially is. The difficult part is feeding the equation with the correct information, and with the correct timing and sequence, etc..

jk4930 13y ago

Here's a 5 min video of AIXI playing Pacman (the description provides details): https://www.youtube.com/watch?v=RhQTWidQQ8U https://www.youtube.com/watch?v=RhQTWidQQ8U Look for YT videos with Marcus Hutter, they're excellent. He explains very good, very systematic. Great stuff.

j2kun 13y ago

I'm surprised there's no reference to computational complexity. I can give a perfectly fine example of a machine that satisfies their definition but would not be considered intelligent because it's inefficient.

j2kun 13y ago

Does anyone know of an overview for people who already know the relevant mathematics? Does their "English" definition have a corresponding mathematical definition?

yetanotherphd 13y ago

For those having trouble getting past the hype to the actual content of AIXI, lesswrong has a nice article [1]. From the article: "The AIXI formalism says roughly to consider all possible computable models of the environment, Bayes-update them on past experiences, and use the resulting updated predictions to model the expected sensory reward of all possible strategies." I will add that the prior over models comes from a measure of model complexity, which is a reasonable way to construct a prior. While I think the idea of connecting deep mathematical formalisms with actual AI goals is mostly hype, these formalisms are still interesting in themselves. There is something very intuitive about how AIXI works, but that doesn't mean it is going to practical for a large range of problems. [1] http://wiki.lesswrong.com/wiki/AIXI http://wiki.lesswrong.com/wiki/AIXI

dinkumthinkum 13y ago
I don't recommend reading anything on that website. That way madness lies.
- yetanotherphd 13y ago
  I don't read lesswrong, but this article is worthy on its own merits. No memetic hazards are lurking in that particular article :-)