Spectral Graph Theory I: basic setup and "the" quadratic form associated to an undirected graph. Lecture 13a of "CS Theory Toolkit": a semester-long graduate course on math and CS fundamentals for research in theoretical computer science, taught at Carnegie Mellon University. Resource for this lecture: "Spectral and Algebraic Graph Theory" book by Spielman Taught by Ryan O'Donnell ( ~odonnell) Course homepage on CMU's Diderot system: Thumbnail photo by Rebecca Kiger ( )