lambda (n.) (λ)

A notion developed in mathematical logic and used as part of the conceptual apparatus underlying FORMAL SEMANTICS. The lambda operator is a device which constructs expressions denoting functions out of other expressions (e.g. those denoting truth values) in a process called lambda abstraction. The process of relating equivalent lambda expressions is known as lambda conversion. Several kinds of lambda calculus have been devised as part of a general theory of functions and logic, functions here being defined as sets of unordered pairs (graphs). The approach has proved attractive to linguists because of its ability to offer a powerful system for formalizing exact meanings and semantic relationships, and lambda notions have helped to inform a number of linguistic theories, notably MONTAGUE GRAMMAR and CATEGORIAL GRAMMAR. (2) In ACOUSTICS, the symbol for wavelength.