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World Models

David Ha, Jürgen Schmidhuber

2018 · arXiv

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From the abstract

We explore building generative neural network models of popular reinforcement learning environments. Our world model can be trained quickly in an unsupervised manner to learn a compressed spatial and temporal representation of the environment. By using features extracted from the world model as inputs to an agent, we can train a very compact and simple policy that can solve the required task. We can even train our agent entirely inside of its own hallucinated dream generated by its world model, and transfer this policy back into the actual environment. An interactive version of this paper is available at https://worldmodels.github.io/

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d110af5ccf
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> it seems that this merely exposes the normal operation. Insufficient images of that person prevented it from abstracting the person components from the background yes my point was that this total failure to abstract (or slice or average or whatever it is that it usually seems to do) appears to me to be neither the intended nor typical mode of operation > children under 1/10 of that age, who have seen only 10% of those images would not make the same kinds of mistakes but then children aren't being fed a stream of unrelated images. they're receiving a wide array of real time sensory input from an environment they're actively operating in consider your examples of the lack…
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of higher level understanding about how the parts of a human "fit together". what practical experience do these models have that could actually convey such an understanding? deriving a proper understanding of mechanics in 3D from one million independent 2D still frames of human hands performing various tasks seems like it should be extremely difficult at best > Could this be trained in? I expect so, but I think it would require multiple engines I think it requires a different sort of training algorithm entirely. work such as https://arxiv.org/abs/1803.10122 suggests to me that there might be little difference between the human ability to abstract and lossy compression. at the same time work such as https://arxiv.org/abs/2205.11502 makes it apparent that in many cases this sort of generalization simply does not happen the way we'd like > the neuron/synapse/neurotransmitter and brainstem/midbrain/cerebellum micro & macro-architectures are vastly different than the computer training models. So, I think we can be confident that something different is happening something being architected differently doesn't necessarily mean that the higher level functionality is any different moreover, in purely functional terms how do you propose to distinguish something that's different from something that's incomplete? ie a smaller piece of a larger whole? if someone constructs for example a passable digital model of the visual cortex of the mouse or human or other animal that's still only a single small piece of the whole so who is and how are we to say that we either have or haven't achieved a meaningful form of abstraction versus merely averaging bits of the training set together? at this point I'm not actually clear where the line between those two things even lies
candiodari
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That may be true, but that's not to simulate. "Dreaming" is used to "simulate", and it's only a hack, in humans probably not even explicitly programmed. The hack is to have the simulator itself ... also be a learned system, and not to simulate the world, because you don't act on the real world, only a tiny part of it that you can measure and actually get into your brain (which is a simplified version of what you see, or a "latent variable"). There's no need to simulate anything that doesn't affect your reasoning. The information flows in reality with an intelligent actor is like this. World (say, a tree falls) -> input representation (e.g. eyes) -> simplified version…
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("latent" version) -> intelligent actor -> muscles -> affects world. Now what everybody thinks of as a simulator is something that simulates the whole thing. But if you insert one more link (output of reasoning agent at time T -> simplified representation at time T+1) you can then run a "simulation": random simplified version ("what if your car became a tree and fell ?") -> intelligent actor -> next input for latent representation ("then what happens ?") For safety reasons, it is probably prudent to disconnect the muscles in this state. You know, so you don't knock out your mother when you dream about boxing. And as you say, this "predict the future" network is probably useful by itself in dealing with the world. So you can catch tennis balls and the like. https://arxiv.org/abs/1803.10122 Or, if you like: https://www.youtube.com/watch?v=dPsXxLyqpfs
TaylorAlexander
Neutral mention · rule
Not a book but if you’re ML curious, I enjoyed reading the World Models paper. It was the first ML paper I read all the way through, and I found it approachable but still technically informative. I later learned the author has been in the AI game for decades, which explains his clear explanations and comfort with the material. PDF link at this page: https://arxiv.org/abs/1803.10122 The interactive web page explains what you’d be reading about: https://worldmodels.github.io/

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