Nuprl - Proof: one one corr rel vs invfuns 1 1 1 1 1 1 1

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At: one one corr rel vs invfuns 1 1 1 1 1 1 1

1. A : Type
2. B : Type
3. R : A

Prop
4.

x:A.

!y:B. R(x;y)
5.

y:B.

!x:A. R(x;y)
6. f : A

B
7.

x:A. R(x;f(x))
8. g : B

A
9.

y:B. R(g(y);y)
10. x : A
11.

!u:A. R(u;f(x))

g(f(x)) = x

By:	FwdThru: Thm* P:(AProp). (!u:A. P(u)) (y,z:A. P(y) P(z) y = z) on [ Hyp:-1 ] Using:[g(f(x)) \| x]

Generated subgoals:

1 R(g(f(x));f(x))
1 step

2 R(x;f(x))
1 step

About:

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