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)