In the meantime, the practical consequence of the “no free lunch” theorem is that there’s no such thing as learning without knowledge. Data alone is not enough. Starting from scratch will only get you to scratch. Machine learning is a kind of knowledge pump: we can use it to extract a lot of knowledge from data, but first we have to prime the pump. Machine learning is what mathematicians call an ill-posed problem: it doesn’t have a unique solution. Here’s a simple ill-posed problem: Which two numbers add up to 1,000? Assuming the numbers are positive, there are five hundred possible answers: 1
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