data manifold two points on the data manifold that's called denoising auto-encoder and that's why those NLP it was largely a pea model i was telling you about do that's called a master to encode particular case of denoising auto-encoder I'm gonna mention a little bit metric learning because it's one of the few cases where it works and it's in fact the only case we know it works in the context of images so it's kind of important and it's those results are reason like last week and then there's architectural methods some of them some