Expander mixing lemma

The Expander Mixing Lemma is a result from the field of graph theory, particularly in the study of expander graphs. Expander graphs are sparse graphs that have strong connectivity properties, which makes them useful in various applications, including computer science, combinatorics, and information theory. The Expander Mixing Lemma provides a quantitative measure of how well an expander graph mixes the vertices when performing random walks on the graph.