EXISTS_UNIQUE_CONV : conv
|- (?! x. P[x]) = (?x. P[x]) /\ (!x x'. P[x] /\ P[x'] ==> (x = x'))where x' is a primed variant of x that does not appear free in the input term. Note that the quantified variable x need not in fact appear free in the body of the input term. For example, EXISTS_UNIQUE_CONV "?!x.T" returns the theorem:
|- (?! x. T) = (?x. T) /\ (!x x'. T /\ T ==> (x = x'))