Research work · 2003

Well-formed formula (WFF)

Patrick C. Fischer

Encyclopedia of Computer Science

Abstract

A well-formed formula (WFF) is a string of symbols that is grammatically (syntactically) correct by virtue of belonging to some language of interest. The problem of testing whether a string is in the language must be decidable (see UNDECIDABLE PROBLEMS). Examples of such languages include WFFs in the propositional calculus, WFFs in the predicate calculus, syntactically correct expressions in most programming languages, arithmetic expressions, and grammatically correct sentences in English.