Editing Formula (section)

===In mathematical logic===
In [[mathematical logic]], a formula (often referred to as a ''[[well-formed formula]]'') is an entity constructed using the symbols and formation rules of a given [[formal language|logical language]].<ref>{{Citation
  |last=Rautenberg
  |first=Wolfgang
  |author-link=Wolfgang Rautenberg
  |doi=10.1007/978-1-4419-1221-3
  |title=A Concise Introduction to Mathematical Logic
  |publisher=[[Springer Science+Business Media]]
  |location=[[New York City|New York, NY]]
  |edition=3rd
  |isbn=978-1-4419-1220-6
  |year=2010
}}</ref> For example, in [[first-order logic]],
:<math>\forall x \forall y (P(f(x)) \rightarrow\neg (P(x) \rightarrow Q(f(y),x,z)))</math>
is a formula, provided that <math>f</math> is a unary function symbol, <math>P</math> a unary predicate symbol, and <math>Q</math> a ternary predicate symbol.