Editing Combinatory logic (section)

==In mathematics==
Combinatory logic was originally intended as a 'pre-logic' that would clarify the role of [[quantifier (logic)|quantified variables]] in logic, essentially by eliminating them. Another way of eliminating quantified variables is [[Willard Van Orman Quine|Quine's]] [[predicate functor logic]]. While the [[expressive power (computer science)|expressive power]] of combinatory logic typically exceeds that of [[first-order logic]], the expressive power of [[predicate functor logic]] is identical to that of first order logic ([[#Quine 1960 1966|Quine 1960, 1966, 1976]]).

The original inventor of combinatory logic, [[Moses Schönfinkel]], published nothing on combinatory logic after his original 1924 paper. [[Haskell Curry]] rediscovered the combinators while working as an instructor at [[Princeton University]] in late 1927.{{sfn|Seldin|2008}} In the late 1930s, [[Alonzo Church]] and his students at Princeton invented a rival formalism for functional abstraction, the [[lambda calculus]], which proved more popular than combinatory logic. The upshot of these historical contingencies was that until theoretical computer science began taking an interest in combinatory logic in the 1960s and 1970s, nearly all work on the subject was by [[Haskell Curry]] and his students, or by [[Robert Feys]] in [[Belgium]]. Curry and Feys (1958), and Curry ''et al.'' (1972) survey the early history of combinatory logic. For a more modern treatment of combinatory logic and the lambda calculus together, see the book by [[Henk Barendregt|Barendregt]],{{sfn|Barendregt|1984}} which reviews the [[model theory|models]] [[Dana Scott]] devised for combinatory logic in the 1960s and 1970s.