This is an old revision of this page, as edited by Onebyone (talk | contribs) at 14:53, 17 December 2003 (Illustrative examples). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 14:53, 17 December 2003 by Onebyone (talk | contribs) (Illustrative examples)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)In logic, WFF is an abbreviation for well-formed formula. That is, given a formal grammar to produce strings, the assertion 'string S is a WFF' only means that it really is produced by the grammar.
For example, in propositional calculus the sequence of symbols is a wff because it is gramatically correct (in fact, it is a tautology). The sequence of symbols is not a wff, because it does not conform to the grammar of propositional calculus.
is a wff because it is gramatically correct (in fact, it is a 
is not a wff, because it does not conform to the grammar of propositional calculus.
Informally, wffs are the sequences of symbols which have meaning in a given logical system.
In mathematics, a WFF is often the basis of a proof, which leads to one of the most notoriously esoteric puns ever used in the name of a product: "WFF 'n Proof: The Game of Modern Logic," by Layman Allen, a professor at the University of Michigan. The board game is designed to teach the principles of symbolic logic to children (in Polish notation), and its name is a pun on whiffenpoof, a nonsense word used as a cheer at Yale University made popular in The Whiffenpoof Song.