| Some definitions of interest. |
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iff | Def P  Q == (P  Q) & (P  Q) |
| | Thm* A,B:Prop. (A  B) Prop |
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injection_type | Def A inj B == {f:(A B)| Inj(A; B; f) } |
| | Thm* A,B:Type. A inj B Type |
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inject | Def Inj(A; B; f) == a1,a2:A. f(a1) = f(a2) B  a1 = a2 |
| | Thm* A,B:Type, f:(A B). Inj(A; B; f) Prop |