Editing Combinatory logic (section)

=== Combinatory terms ===

A combinatory term has one of the following forms:

{| class="wikitable"
|-
! Syntax !! Name !! Description
|-
| x || Variable || A character or string representing a combinatory term.
|-
| P || Primitive function || One of the combinator symbols '''I''', '''K''', '''S'''.
|-
| (M N) || Application || Applying a function to an argument. M and N are combinatory terms. 
|}

The primitive functions are ''combinators'', or functions that, when seen as lambda terms, contain no [[free variable]]s.

To shorten the notations, a general convention is that {{tmath|(E_1 E_2 E_3 ... E_n)}}, or even {{tmath|E_1 E_2 E_3... E_n}}, denotes the term {{tmath|(...((E_1 E_2) E_3)... E_n)}}. This is the same general convention (left-associativity) as for multiple application in lambda calculus.