These are notes for the Fall 2020 semester version of the Yale course CPSC 465/565 Theory of Distributed Systems. This document also incorporates the lecture schedule and assignments, as well as some sample assignments from previous semesters. Because this is a work in progress, it will be updated frequently over the course of the semester. 

The most recent version of these notes will be available at http://www.cs.yale.edu/homes/aspnes/classes/465/notes.pdf. More stable archival versions may be found at https://arxiv.org/abs/2001.04235. 

Not all topics in the notes will be covered during this semester. Some chapters have not been updated and are marked as possibly out of date. 

Much of the structure of the course follows the textbook, Attiya and Welch's Distributed Computing [AW04], with some topics based on Lynch's Distributed Algorithms [Lyn96] and additional readings from the research literature. In most cases you'll find these materials contain much more detail than what is presented here, so it may be better to consider this document a supplement to them than to treat it as your primary source of information.