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A backwards E with an exclamation mark, asserting a unique solution.
Also known as: Unique existential quantifier, Exists exactly one, E-bang
The unique-existence quantifier asserts that exactly one object satisfies a condition — not at least one, and not more than one. It is shorthand for a longer statement combining existence with a uniqueness clause, and expanding it is how the assertion is actually proved.
Asserts that exactly one object satisfies the stated condition: existence and uniqueness together.
Contexts: Mathematics
Abbreviates a longer formula pairing an existence claim with a clause saying any two witnesses are equal, which is how such a statement is proved.
Contexts: Mathematics
A capital letter E reversed left to right, followed immediately by an upright stroke with a dot beneath it.
The same quantifier with a uniqueness claim attached.