lambda calculus

Coined by Alonzo Church after the use of the Greek letter lambda (λ) as the basic abstraction operator in the calculus.

lambda calculus (countable and uncountable, plural lambda calculi)

1. (computing theory) Any of a family of functionally complete algebraic systems in which lambda expressions are evaluated according to a fixed set of rules to produce values, which may themselves be lambda expressions.
   • 2009 March 2, John C. Baez with Mike Stay, “Physics, Topology, Logic and Computation: A Rosetta Stone”, in (Please provide the book title or journal name)‎, page 50:

     In the 1930s, while Turing was developing what are now called ‘Turing machines’ as a model for computation, Church and his student Kleene were developing a different model, called the ‘lambda calculus’ [29, 63]. While a Turing machine can be seen as an idealized, simplified model of computer hardware, the lambda calculus is more like a simple model of software.

• alpha conversion
• beta reduction
• eta conversion
• lambda term

• simply typed lambda calculus
• typed lambda calculus

• calculus
• lambda
• lambda abstraction
• lambda expression

• combinator
• functionally complete
• recursive function
• Turing machine