  Pylearn2 is a machine learning research library. This does not just mean that
it is a collection of machine learning algorithms that share a common API; it
means that it has been designed for flexibility and extensibility in order to
facilitate research projects that involve new or unusual use cases. In this
paper we give a brief history of the library, an overview of its basic
philosophy, a summary of the library's architecture, and a description of how
the Pylearn2 community functions socially.
