ndefinition surjective ≝
λA,B.λS: ext_powerclass A.λT: ext_powerclass B.λf:unary_morphism A B.
∀y. y ∈ T → ∃x. x ∈ S ∧ f x = y.
ndefinition surjective ≝
λA,B.λS: ext_powerclass A.λT: ext_powerclass B.λf:unary_morphism A B.
∀y. y ∈ T → ∃x. x ∈ S ∧ f x = y.