In September, 2022, David Brailsford, Brian Kernighan and William Ritchie published a paper entitled
How did Dennis Ritchie Produce his PhD Thesis? A Typographical Mystery
at DocEng22, an annual conference devoted to document engineering.

The DocEng paper focused on one of several mysteries about Dennis Ritchie's 1968 PhD thesis, namely, how was it produced? It is nearly 200 pages long, full of intricate mathematical expressions, all very precisely positioned, and almost free of typographical errors. It's a tour de force of precision typing at a time just before the advent of computerized document preparation software and suitable hardware.

To summarize the DocEng paper, we simply don't know, though we have some informed speculations and a lot of unanswered questions.

Space limitations prevented us from including a number of large images that illustrate the complexity, the precision, and the mysteries. This web page shows a number of high resolution examples of character spacing from Dennis's thesis. All of the figures were produced by Katie LaSeur of TheCreativeFold, to whom we express our deep gratitude.

The DocEng paper is available here. Dave Brailsford's keynote presentation at DocEng22 is available at this Google link. This is a standard resolution (720P) 42 minute video that was first broadcast on Wed 26th Sept 2022 at approximately 6 am Pacific Time. DocEng 2022 was a virtual conference because of the COVID pandemic so the material in the video itself was filmed a few days earlier. Our thanks again to Sean Riley for video work.

There are also three versions of the thesis itself:

On March 16, 2023, Hacker News had a thread devoted to this paper, with much speculation. Naturally the story went to the great beyond (that is, off the first page) rather quickly, but it's here if anyone is interested.

Bill Ritchie maintains a web site devoted to Dennis's thesis at; it has further information about the thesis itself, and also on the other great mystery: why did Harvard not accept the thesis and why did Dennis never receive his PhD?


Exhibit 1

Exhibit 2

Exhibit 3

Exhibit 4

Exhibit 5

Exhibit 6

Fri Mar 17 18:44:10 EDT 2023