functional application/composition

Terms used in FORMAL LINGUISTICS in their conventional mathematical senses, and adapted in CATEGORIAL GRAMMAR to RULES which combine (a) an EXPRESSION of some complex category X/Y with an expression of some category Y to form an expression of category X (functional or function application), and (b) an expression of some complex category X/Y with an expression of some category Y/Z to form an expression of category X/Z (functional or function composition). The terms are also used for similar rules in TYPE-theoretic approaches to SEMANTICS.