Are neural networks really abandonware?

I am planning to use neural networks for approximating a value function in a reinforcement learning algorithm. I want to do that to introduce some generalization and flexibility on how I represent states and actions.

Now, it looks to me that neural networks are the right tool to do that, however I have limited visibility here since I am not an AI expert. In particular, it seems that neural networks are being replaced by other technologies these days, e.g. support vector machines, but I am unsure if this is a fashion matter or if there is some real limitation in neural networks that could doom my approach. Do you have any suggestion开发者_开发问答?

Thanks,

Tunnuz

It's true that neural networks are no longer in vogue, as they once were, but they're hardly dead. The general reason for them falling from favor was the rise of the Support Vector Machine, because they converge globally and require fewer parameter specifications.

However, SVMs are very burdensome to implement and don't naturally generalize to reinforcement learning like ANNs do (SVMs are primarily used for offline decision problems).

I'd suggest you stick to ANNs if your task seems suitable to one, as within the realm of reinforcement learning, ANNs are still at the forefront in performance.

Here's a great place to start; just check out the section titled "Temporal Difference Learning" as that's the standard way ANNs solve reinforcement learning problems.

One caveat though: the recent trend in machine learning is to use many diverse learning agents together via bagging or boosting. While I haven't seen this as much in reinforcement learning, I'm sure employing this strategy would still be much more powerful than an ANN alone. But unless you really need world class performance (this is what won the netflix competition), I'd steer clear of this extremely complex technique.

It seems to me that neural networks are kind of making a comeback. For example, this year there were a bunch of papers at ICML 2011 on neural networks. I would definitely not consider them abandonware. That being said, I would not use them for reinforcement learning.

Neural networks are a decent general way of approximating complex functions, but they are rarely the best choice for any specific learning task. They are difficult to design, slow to converge, and get stuck in local minima.

If you have no experience with neural networks, then you might be happier to you use a more straightforward method of generalizing RL, such as coarse coding.

Theoretically it has been proved that Neural Networks can approximate any function (given an infinite number of hidden neurons and the necessary inputs), so no I don't think the neural networks will ever be abandonwares.

SVM are great, but they cannot be used for all applications while Neural Networks can be used for any purpose.

Using neural networks in combination with reinforcement learning is standard and well-known, but be careful to plot and debug your neural network's convergence to check that it works correctly as neural networks are notoriously known to be hard to implement and learn correctly.

Be also very careful about the representation of the problem you give to your neural network (ie: the inputs nodes): could you, or could an expert, solve the problem given what you give as inputs to your net? Very often, people implementing neural networks don't give enough informations for the neural net to reason, this is not so uncommon, so be careful with that.