- (Wikipedia, 2009) ⇒ http://en.wikipedia.org/wiki/Well-formed_formula
- In mathematical logic, a well-formed formula, shortly wff, often simply formula, is a word (i.e. a finite sequence of symbols from a given alphabet) which is part of a formal language. A formal language can be considered to be identical to the set containing all and only its formulas.
- Formulas are a standard topic in introductory logic, and are covered by all introductory textbooks, including Enderton (2001), Gamut (1990), and Kleene (1967)
- A statement that is expressed in a valid, syntactically correct, manner
- FOL: formulae that are built from a vocabulary, the logical symbols of FOL and first-order variables according to the syntax rules of FOL.
- CYC Glossary http://www.cyc.com/cycdoc/ref/glossary.html