The unique existential quantifer is the symbol ∃!. For example,
means "there exists an unique x such that x-2 = 4".
History of the Quantifer
TODO
See Existential quantification for details.
... Wesley Powell, (1834-1902), explorer, environmentalist Nathaniel Pryor[?], (c 1785-1850), US explorer Pytheas, (died 1984), Greek explorer who visited Britain ...