Well-Formed Formula

See: Logic Sentence, Formal Language Sentence, Truth-Bearing Proposition, Proven Mathematical Statement.

References

(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.^[1] A formal language can be considered to be identical to the set containing all and only its formulas.
  A formula is a syntactic formal object that can be informally given a semantic meaning.

↑ Formulas are a standard topic in introductory logic, and are covered by all introductory textbooks, including Enderton (2001), Gamut (1990), and Kleene (1967)

http://en.wiktionary.org/wiki/well-formed_formula
- A statement that is expressed in a valid, syntactically correct, manner
http://www.coli.uni-saarland.de/projects/milca/courses/comsem/xhtml/d0e1-gloss.xhtml
- 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
- well-formed formula: A formula in CycL is well-formed if it conforms to the syntax of CycL and passes all the restrictions on arity and argument types of the relations that are used in it.