A 13th-Century Enumeration Algorithm, Ignored for 700 Years
Summary
A 13th-Century treatise by Abraham Aboulafia is presented as a recursive method for enumerating all permutations of an n-letter word (Tserouf). The article explains the two initial rules for three letters, then shows how rotating the first letter to the end extends the method to longer words, revealing a single, elegant recursive process that generates all permutations exactly once. It also notes historical parallels and a connection to a 1984 algorithm by Shimon Zaks and Gates, framing the discovery within a broader mathematical lineage.