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>> No.14888514 [View]
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14888514

Why can't i do:
VyEx(Axy)
1. Ex(Axy) Universal Instantiation of y
2. A(ay) Existential Instantiation of x to constant a
3. Vy(Aay) Universal Generalization of y
4. ExVy(Axy) Existential generalization of x

I know step 3 is not allowed, but i'm not sure the rigorous, formal reason why.

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