1 | 1. A: Type 2. B: Type 3. f: A B A 4. a:A, b1,b2:B. f(a,b1) = f(a,b2)  b1 = b2 5. a,a':A. Dec( b:B. a' = f(a,b)) 6. p: A B < 1of(p),f(1of(p),2of(p)) > {p:(A A)| b:B. 2of(p) = f(1of(p),b) A } | 1 step |
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2 | 1. A: Type 2. B: Type 3. f: A B A 4. a:A, b1,b2:B. f(a,b1) = f(a,b2)  b1 = b2 5. a,a':A. Dec( b:B. a' = f(a,b)) Bij(A; A; Id) | 1 step |
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3 | 1. A: Type 2. B: Type 3. f: A B A 4. a:A, b1,b2:B. f(a,b1) = f(a,b2)  b1 = b2 5. a,a':A. Dec( b:B. a' = f(a,b)) Bij(A B; {p:(A A)| b:B. 2of(p) = f(1of(p),b) A }; p. < 1of(p),f(1of(p),2of(p)) > ) | 10 steps |
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4 | 1. A: Type 2. B: Type 3. f: A B A 4. a:A, b1,b2:B. f(a,b1) = f(a,b2)  b1 = b2 5. a,a':A. Dec( b:B. a' = f(a,b)) (Id,Id) o p. < 1of(p),f(1of(p),2of(p)) > = Id o ( p. < 1of(p),f(1of(p),2of(p)) > ) A B A A | 1 step |