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The Limitations of Deep Learning

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Re: The Limitations of Deep Learning

#41

Earlier quoted context omitted.

turns out it's very hard to model a thing that we don't know how it actually works

To be fair, we do understand how neurons work, at least on a singular level. Perceptrons model that quite well.

Implementing a basic perceptron classifier is an undergrad homework assignment. Biological modeling of neurons is a work of decades:

http://www.genesis-sim.org/

https://www.neuron.yale.edu/neuron/what_is_neuron

Re: The Limitations of Deep Learning

#42
I think the requirement for a large amount of data is the biggest objection to the reflex "AI will replace [insert your profession here] soon" that many techies, in particular on HN, have.

There are many professions where there is very little data available to learn from. In some case (self-driving), companies will invest large amount of money to build this data, by running lots of test self-driving cars, or paying people to create the data, and it is viable given the size of the market behind. But the typical high-value intellectual profession is often a niche market with a handful of specialists in the world. Think of a trader of financial institutions bonds, or a lawyer specialized in cross-border mining acquisitions, a physician specialist of a rare disease or a salesperson for aviation parts. What data are you going to train your algorithm with?

The second objection, probably equally important, also applies to "software will replace [insert your boring repetitive mindless profession here]", even after 30 years of broad adoption of computers. If you decide to automate some repetitive mundane tasks, you can spare the salary of the guys who did these tasks, but now you need to pay the salary of a full team of AI specialists / software developers. Now for many tasks (CAD, accounting, mailings, etc), the market is big enough to justify a software company making this investment. But there is a huge number of professions where you are never going to break even, and where humans are still paid to do stupid tasks that a software could easily do today (even in VBA), and will keep doing so until the cost of developing and maintaining software or AI has dropped to zero.

I don't see that happening in my life. In fact I am not even sure we are training that many more computer science specialists than 10 years ago. Again, didn't happen with software for very basic things, why would it happen with AI for more complicated things.

Re: The Limitations of Deep Learning

#43

Earlier quoted context omitted.

turns out it's very hard to model a thing that we don't know how it actually works

To be fair, we do understand how neurons work, at least on a singular level. Perceptrons model that quite well.

But how does a neuron decide to grow new axons or how to change input weights? Biological neurons does this when solving tasks and not just during training. Isn't it possible that human-like intelligence depends on the network being dynamic? For example, when you play a game for the first time a lot of things suddenly starts to click, couldn't that be the result of new connections forming or at least some weights being changed? If this is true then it would be impossible to create a general game playing AI with human-like performance using our current model.

Re: The Limitations of Deep Learning

#44
post #14

This point is very well made: 'local generalization vs. extreme generalization.' Advanced NN's today can locally generalize quite well and there's a lot of research spent to inch their generalization further out. This will probably be done by increasing NN size or increasing the NN building-blocks complexity.

Or maybe increasing NN size/complexity is the 21st century version of adding epicycles to make geocentrism work. http://wiki.c2.com/?AddingEpicycles

Heh, but it makes geocentrism works better! And we don't yet know how 21st century heliocentrism will look like, while adding epicycles is less daunting.

Re: The Limitations of Deep Learning

#45
Surely we shouldn't rush to anthropomorphize neural networks, but we'd ignoring the obvious if we didn't at least note that neural networks do seem to share some structural similarities with our own brains, at least at a very low level, and that they seem to do well with a lot of pattern-recognition problems that we've traditionally considered to be co-incident with brains rather than logical systems.

The article notes, "Machine learning models have no access to such experiences and thus cannot "understand" their inputs in any human-relatable way". But this ignores a lot of the subtlety in psychological models of human consciousness. In particular, I'm thinking of Dual Process Theory as typified by Kahneman's "System 1" and "System 2". System 1 is described as a tireless but largely unconscious and heavily biased pattern recognizer - subject to strange fallacies and working on heuristics and cribs, it reacts to it's environment when it believes that it recognizes stimuli, and notifies the more conscious "System 2" when it doesn't.

At the very least it seems like neural networks have a lot in common with Kahneman's "System 1".

Re: The Limitations of Deep Learning

#46
post #5

As someone primarily interested in interpretation of deep models, I strongly resonate with this warning against anthropomorphization of neural networks. Deep learning isn't special; deep models tend to be more accurate than other methods, but fundamentally they aren't much closer to working like the human brain than e.g. gradient boosting models. I think a lot of the issue stems from layman explanations of neural net…

The anthropomorphization was done by academic researchers to gain/increase funding for themselves and the field. You can read the papers and see. This is commonly done for marketing purposes and is important since the pool of research money can be limited.

Re: The Limitations of Deep Learning

#47

I'm excited to hear about how we bring about abstraction. I was wondering how a NN would go about discovering F = ma and the laws of motion. As far as I can tell, it has a lot of similarities to how humans would do it. You'd roll balls down slopes like in high school and get a lot of data. And from that you'd find there's a straight line model in there if you do some simple transformations. But how would you come to…

I've had similar thoughts when it comes to recognizing the underlying (potential) simplicity of a phenomena of interest.

For example, consider a toy experiment where you take dozens of high speed sensors pointed a rig in order to study basic spring dynamics (i.e. Hooke's law).

You could apply "big data analytics" or ML methods to break apart the dynamics to predict future positions past on past positions.

But hopefully, somewhere along the way, you have some means of recognizing that it is a simple 1D phenomena and that most of the volume of data that you collected is fairly pointless for that goal.

Re: The Limitations of Deep Learning

#48
post #47

I'm excited to hear about how we bring about abstraction. I was wondering how a NN would go about discovering F = ma and the laws of motion. As far as I can tell, it has a lot of similarities to how humans would do it. You'd roll balls down slopes like in high school and get a lot of data. And from that you'd find there's a straight line model in there if you do some simple transformations. But how would you come to…

I've had similar thoughts when it comes to recognizing the underlying (potential) simplicity of a phenomena of interest. For example, consider a toy experiment where you take dozens of high speed sensors pointed a rig in order to study basic spring dynamics (i.e. Hooke's law). You could apply "big data analytics" or ML methods to break apart the dynamics to predict future positions past on past positions. But hopeful…

Almost all deep learning progress is optimization on a scale going from 'incredibly inefficient use of space and time' to 'quite wasteful' to 'optimal'. You're jumping the gap from 'quite wasteful' to 'optimal' in one step because you understand the problem. If you could find a way to do that algorithmically you likely would have created an actual AI.

Re: The Limitations of Deep Learning

#49
the only real success of deep learning so far has been the ability to map space X to space Y using a continuous geometric transform, given large amounts of human-annotated data.

Yes, but that's what human's do too, only much much better from the generalized perspective.

I think that fundamentally this IS the paradigm for AGI, but we are in the pre-infant days of optimization across the board (data, efficiency, tagging etc...).

So I wholeheartedly agree with the post, that we shouldn't cheer yet, but we should also recognize that we are on the right track.

I say all this because prior to getting into DL and more specifically Reinforcement Learning (which is WAY under studied IMO), I was working with Bayesian Expert Systems as a path to AI/AGI. RL totally transformed how I saw the problem and in my mind offers a concrete pathway to AGI.

Re: The Limitations of Deep Learning

#50
post #42

I think the requirement for a large amount of data is the biggest objection to the reflex "AI will replace [insert your profession here] soon" that many techies, in particular on HN, have. There are many professions where there is very little data available to learn from. In some case (self-driving), companies will invest large amount of money to build this data, by running lots of test self-driving cars, or paying p…

> and will keep doing so until the cost of developing and maintaining software or AI has dropped to zero.

I have no idea about the progress of AI, but normal software will get an order of magnitude cheaper to develop as we slowly wake up from the Unix/worse-is-better/everything-is-text mindset and abandon the dynamically typed and imperative languages, broken systems abstractions, etc. that hold us back.

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