And Rosta wrote:
I must admit I haven't come across an exposition of the iota operator such that I have understood exactly what it is.
It is +veridical -definite -specific +singular: \iota x p(x) = "the one x such that p(x) is true (or nothing if there is no such x)". Russell's example: \iota x (x wrote _Waverly_) means "the (unique) author of _Waverly_" and refers to Walter Scott. Typographical note: the iota is rotated 180 degrees. -- Not to perambulate || John Cowan <jcowan@reutershealth.com> the corridors || http://www.reutershealth.com during the hours of repose || http://www.ccil.org/~cowan in the boots of ascension. \\ Sign in Austrian ski-resort hotel