Explore constant-round interactive proof systems in this graduate-level computational complexity theory lecture from Carnegie Mellon University. Delve into topics such as MA and AM, BPP, characterization of AM, interactive proofs, Merlin-Arthur proofs, private coins, efficient error reduction, and parallel repetition. Learn about polynomials, Arthur's coins and messages, Martha's final message, MA AM, and MA L. Examine concepts like Arthur-Merlin, fishing, sketching, fare reduction, amplification, and AMA. Gain insights into translation and compression within the context of interactive proof systems. This lecture, part of CMU's Course 15-855 in Fall 2017, is taught by Ryan O'Donnell and includes suggested readings from Arora-Barak Chapters 8.2.1 and 8.2.2.