What is Entropy? A (measured) Dynamical Perspective

This was written as part of a reading group I organized at my university. These notes are meant to explain probability theory, Shannon entropy, and measured dynamical entropy, with one application. My sources are Kerr and Li’s Ergodic Theory and Claude Shannon’s paper A Mathematical Theory of Communication.

Rotation Numbers and the Poincare Classification

This was written as part of a reading group I organized at my university. The text we are using is Katok and Hasselblatt’s First Course in Dynamics. These notes are meant to explain rotation numbers of circle homeomorphisms, and some general dynamical concepts like factor maps and homoclinicity. Denjoy’s theorem is also discussed.

Lie Groups and their Lie Algebras

There is a saying that “groups, like men, will be known by their actions.” The groups we are interested in here are known by their actions as linear transformations on vector spaces (of finite dimension, over or ). Thus for every we must have for all scalars and . Since we require that , theContinue reading “Lie Groups and their Lie Algebras”