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An inverted capital A, the universal quantifier of formal logic.
Also known as: Universal quantifier, Upside-down A
∀ is the universal quantifier: it asserts that a statement holds for every member of a set. Gerhard Gentzen introduced it in 1935 as an inverted A, for the German alle, matching Peano's earlier inverted E for existence.
Is encoded as U+2200 FOR ALL in the Mathematical Operators block.
Contexts: Mathematics
Asserts that what follows holds for every member of the set being quantified over, and is read 'for all' or 'for every'.
Contexts: Mathematics
Was introduced by Gerhard Gentzen in 1935 as an inverted A, chosen for the German word alle, deliberately echoing Peano's inverted E for existence.
Contexts: Mathematics
A capital Latin A turned upside down: two diagonal strokes meeting at a point below, joined partway up by a horizontal crossbar.
The two quantifiers of first-order logic; each is the negation of the other applied to a negated statement.