The Goals of Unsupervised Learning
Without a desired output or reinforcement signal it is
much less obvious what the goal is.
Discover useful structure in large data sets without
requiring a supervisory signal
Create representations that are better for subsequent
supervised or reinforcement learning
Build a density model that can be used to:
Classify by seeing which model likes the test case data most
Monitor a complex system by noticing improbable states.
Extract interpretable factors (causes or constraints)
Improve learning speed for high-dimensional inputs
Allow features within a layer to learn independently
Allow multiple layers to be learned greedily.