But Knuth also points to the recent publication of "one of the most important sections of The Art of Computer Programming" in preliminary paperback form: Volume 4, Fascicle 6: Satisfiability. ("Given a Boolean function, can its variables be set to at least one pattern of 0s and 1 that will make the function true?")
Here's an excerpt from its back cover: Revolutionary methods for solving such problems emerged at the beginning of the twenty-first century, and they've led to game-changing applications in industry. These so-called "SAT solvers" can now routinely find solutions to practical problems that involve millions of variables and were thought until very recently to be hopelessly difficult.
"in several noteworthy cases, nobody has yet pointed out any errors..." Knuth writes on his site, adding "I fear that the most probable hypothesis is that nobody has been sufficiently motivated to check these things out carefully as yet." He's uncomfortable printing a hardcover edition that hasn't been fully vetted, and "I would like to enter here a plea for some readers to tell me explicitly, 'Dear Don, I have read exercise N and its answer very carefully, and I believe that it is 100% correct,'" where N is one of the exercises listed on his web site.
Elsewhere he writes that two "pre-fascicles" -- 5a and 5B -- are also available for alpha-testing. "I've put them online primarily so that experts in the field can check the contents before I inflict them on a wider audience. But if you want to help debug them, please go right ahead."