If you are looking for the most recent official material, you can explore the following: Go to product viewer dialog for this item.
Knuth has described Volume 6 as a deep dive into the . Unlike the "inner core" of the first five volumes, Volume 6 and the planned Volume 7 (Compiler Techniques) are considered specialized offshoots.
: These have been the core of the series since the late 60s and early 70s.
Art Of Computer Programming, The, Volumes 1-4B, Boxed By Donald Knuth
The wait for Volume 6 is largely due to Knuth’s commitment to accuracy and the sheer volume of new computer science research that he must synthesise into the series. For example, he famously took an eight-year "detour" to invent the TeX typesetting system just so his books would look right. Where to Find Authentic TAOCP Content
: Originally planned as one book, it has expanded into several sub-volumes (4A, 4B, and the upcoming 4C/4D) due to the vast growth of combinatorial algorithms.
To understand why Volume 6 is not yet available, it is helpful to look at the massive scope of the current work: