Ok, 37 comments so far and NOT ONE is about the talk itself? Come on, people!<p>I went to the talk and frankly I didn&#x27;t follow most of it. I also didn&#x27;t get any connection to trees. But it was interesting to learn that people have studied sequences (codes) and have proven theorems about properties of such codes. I had no idea that this was an area of study.<p>Tidbits:<p>Knuth&#x27;s Commafree Eastman prover is written in C (actually CWEB, a literate programming toolset).<p>Knuth has memorized a bunch of digits of pi in binary using a mnemonic for remembering pi in octal.