Donald Knuth is an American computer scientist, mathematician, and professor emeritus at Stanford University. He is best known for being the author of The Art of Computer Programming series of books.
A commafree code is a set of codewords that can be read easily without spaces or other delimiters between words.
In 1965, Willard Eastman discovered a beautiful but underappreciated way to construct commafree block codes of all odd lengths, over an infinite alphabet. Professor Knuth explains this construction and its interesting connection to questions of iteration versus recursion.