Inside Facebook's AI Workshop

Within Facebook's cavernous Building 20, about halfway between the lobby (panoramic views of the Ravenswood Slough) and the kitchen (hot breakfast, smoothies, gourmet coffee), in a small conference room called Lollapalooza, Joaquin Candela is trying to explain artificial intelligence to a layperson. Candela -- bald, compact, thoughtful -- runs Facebook's Applied Machine Learning (AML) group, the engine room of AI at Facebook, which increasingly makes it the engine room of Facebook in general. "Look, a machine learning algorithm really is a lookup table, right? Where the key is the input, like an image, and the value is the label for the input, like'a horse.' I have a bunch of examples of something. I give the algorithm as many as I can. And the algorithm keeps those in a table. Then, if a new example comes along -- or if I tell it to watch for new examples -- well, the algorithm just goes and looks at all those examples we fed it. It's trying to decide, 'Is this new thing a horse? If it's right, the image gets put in the'This is a horse' group, and if it's wrong, it gets put in the'This isn't a horse' group. Next time, it has more data to look up. One challenge is how do we decide how similar a new picture is to the ones stored in the table. One aspect of machine learning is to learn similarity functions. Another challenge is, What happens when your table grows really large? For every new image, you would need to make a zillion comparisons…. So another aspect of machine learning is to approximate a large stored table with a function instead of going through every image. The function knows how to roughly estimate what the corresponding value should be. This is what learning is about."