Anything can be expressed by a neural network to some arbitrary degree of precision. That's the whole point. The hard part isn't expressing the thing but gettin

Anything can be expressed by a neural network to some arbitrary degree of precision. That's the whole point. The hard part isn't expressing the thing but getting the machine to figure out how to express it correctly on it's own. There's also no way to prove your learning algorithm actually works outside of toy problems like this which is why ML is really only good for data mining rather than steering a car.