  Autocatalytic sets are self-catalyzing and self-sustaining chemical reaction
networks that are believed to have played an important role in the origin of
life. They have been studied extensively both theoretically as well as
experimentally. This short note provides (1) a complete and formal definition
of autocatalytic sets (or RAF sets), and (2) an efficient algorithm to detect
such sets in arbitrary reaction networks. Although both have been presented in
various forms in earlier publications, this note serves as a concise and
convenient reference.
