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(the bijections from A onto B)

Who Cites bijection type?
bijection_typeDef  A bij B == {f:(AB)| Bij(A; B; f) }
Thm*  A,B:Type. A bij B  Type
bijectDef  Bij(A; B; f) == Inj(A; B; f) & Surj(A; B; f)
Thm*  A,B:Type, f:(AB). Bij(A; B; f)  Prop
surjectDef  Surj(A; B; f) == b:B. a:A. f(a) = b
Thm*  A,B:Type, f:(AB). Surj(A; B; f)  Prop
injectDef  Inj(A; B; f) == a1,a2:A. f(a1) = f(a2)  B  a1 = a2
Thm*  A,B:Type, f:(AB). Inj(A; B; f)  Prop

Syntax:A bij B has structure: bijection_type(A; B)

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