Editing Arity (section)

=== Unary ===
Examples of [[unary operator]]s in mathematics and in programming include the [[unary minus]] and plus, the increment and decrement operators in [[C (programming language)|C]]-style languages (not in logical languages), and the [[Successor function|successor]], [[factorial]], [[Multiplicative inverse|reciprocal]], [[floor function|floor]], [[ceiling function|ceiling]], [[fractional part]], [[sign function|sign]], [[absolute value]], [[square root]] (the principal square root), [[complex conjugate]] (unary of "one" [[complex number]], that however has two parts at a lower level of abstraction), and [[Norm (mathematics)|norm]] functions in mathematics.  In programming the [[two's complement]], [[Reference (computer science)|address reference]], and the [[logical NOT]] operators are examples of unary operators.

All functions in [[lambda calculus]] and in some [[functional programming language]]s (especially those descended from [[ML (programming language)|ML]]) are technically unary, but see [[#n-ary|n-ary]] below.

According to [[Willard Van Orman Quine|Quine]], the Latin distributives being ''singuli'', ''bini'', ''terni'', and so forth, the term "singulary" is the correct adjective, rather than "unary".<ref>
{{Citation
  | last = Quine
  | first = W. V. O.
  | title = Mathematical logic
  | year = 1940
  | place = Cambridge, Massachusetts
  | publisher = Harvard University Press
  | page=13
}}</ref> [[Abraham Robinson]] follows Quine's usage.<ref>
{{Citation
  | last = Robinson
  | first = Abraham
  | title = Non-standard Analysis
  | year = 1966
  | place = Amsterdam
  | publisher = North-Holland
  | page=19
}}</ref>

In philosophy, the adjective ''monadic'' is sometimes used to describe a [[monadic predicate calculus|one-place relation]] such as 'is square-shaped' as opposed to a [[binary relation|two-place relation]] such as 'is the sister of'.