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An arrow with two heads, a surjection.
Also known as: Surjection arrow, Arrow with two nested heads, Onto arrow, Epic arrow
A doubled arrowhead marks a surjection — the map covers the whole target. The pair of decorated arrows, hook for injective and double head for surjective, lets a diagram state the properties of every map in it without a word of prose.
Denotes an epimorphism: a map that is surjective, or its categorical generalisation.
Contexts: Mathematics
Pairs with the hooked arrow so a commutative diagram can state injectivity and surjectivity graphically rather than in accompanying text.
Contexts: Mathematics
A horizontal stroke ending right in two nested arrowheads, one behind the other.