The unique existential quantifer is the symbol ∃!. For example,
means "there exists an unique x such that x-2 = 4".
History of the Quantifer
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See Existential quantification for details.
... Prizes Physics - Lord John William Strutt Rayleigh[?] Chemistry - Sir William Ramsay Medicine - Ivan Petrovich Pavlov Literature - Frédéric Mistral, ...