More General Usage
Iff is used outside the field of logic, wherever logic is applied, especially in mathematical discussions. It has the same meaning as above: it is an abbreviation for if and only if, indicating that one statement is both necessary and sufficient for the other. This is an example of mathematical jargon. (However, as noted above, if, rather than iff, is more often used in statements of definition.)
The elements of X are all and only the elements of Y is used to mean: "for any z in the domain of discourse, z is in X if and only if z is in Y."
Read more about this topic: If And Only If
Famous quotes containing the words general and/or usage:
“All the critics who could not make their reputations by discovering you are hoping to make them by predicting hopefully your approaching impotence, failure and general drying up of natural juices. Not a one will wish you luck or hope that you will keep on writing unless you have political affiliations in which case these will rally around and speak of you and Homer, Balzac, Zola and Link Steffens.”
—Ernest Hemingway (1899–1961)
“...Often the accurate answer to a usage question begins, “It depends.” And what it depends on most often is where you are, who you are, who your listeners or readers are, and what your purpose in speaking or writing is.”
—Kenneth G. Wilson (b. 1923)