FYI -- from DEK: https://cs.stanford.edu/~uno/news.html Volume 4B will begin with a special section called 'Mathematical Preliminaries Redux', which extends the 'Mathematical Preliminaries' of Section 1.2 in Volume 1 to things that I didn't know about in the 1960s. Most of this new material deals with probabilities and expectations of random events; there's also an introduction to the theory of martingales. You can have a sneak preview by looking at the current draft of pre-fascicle 5a (52 pages), last updated ***18 January 2017.*** As usual, rewards will be given to whoever is first to find and report errors or to make valuable suggestions. I'm particularly interested in receiving feedback about the exercises (of which there are 125) and their answers (of which there are 125). https://cs.stanford.edu/~uno/fasc5a.ps.gz