| Some definitions of interest. |
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biject | Def Bij(A; B; f) == Inj(A; B; f) & Surj(A; B; f) |
| | Thm* A,B:Type, f:(A B). Bij(A; B; f) Prop |
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iff | Def P  Q == (P  Q) & (P  Q) |
| | Thm* A,B:Prop. (A  B) Prop |
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inv_funs_2 | Def InvFuns(A;B;f;g) == ( x:A. g(f(x)) = x) & ( y:B. f(g(y)) = y) |
| | Thm* f:(A B), g:(B A). InvFuns(A;B;f;g) Prop |