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:
“If men would avoid that general language and general manner in which they strive to hide all that is peculiar and would say only what was uppermost in their own minds after their own individual manner, every man would be interesting.”
—Ralph Waldo Emerson (1803–1882)
“I am using it [the word ‘perceive’] here in such a way that to say of an object that it is perceived does not entail saying that it exists in any sense at all. And this is a perfectly correct and familiar usage of the word.”
—A.J. (Alfred Jules)