A system for reducing the operational notation of logic, mathematics or a functional language to a sequence of modifications to the input data structure. First introduced in the 1920' s by Schoenfinkel. Re-introduced independently by Haskell Curry in the late 1920' s (who quickly learned of Schoenfinkel' s work after he had the idea). Curry is really responsible for most of the development, at least up until work with Feys in 1958. See combinator. (1995-01-05)