A 13th-Century Enumeration Algorithm, Ignored for 700 Years

This is the first article in a series about a discovery I made while researching Tserouf in the writings of the Kabbalist Abraham Aboulafia (1240 – after 1291). Tserouf is the Kabbalistic art of permuting the letters — and, in plain mathematical terms, it is the enumeration of all the permutations of an n-letter word. The context In Or ha-Sekhel (“The Light of the Intellect”), Aboulafia prescribes a systematic method for enumerating all the possible arrangements of an n-letter word. The method...