Nuprl - Proof: inj point deletion inj 1 1 1 1

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At: inj point deletion inj 1 1 1 1

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

B
4. Inj(A; B; f)
5. a : A
6. f

{x:A|

x = a }

{y:B|

y = f(a) }
7. f(a)

B
8. a1 : {x:A|

x = a }
9. a2 : {x:A|

x = a }
10. f(a1) = f(a2)
11.

f(a1) = f(a)

a1 = a2

By:	FwdThru: Inj(A; B; f) on [ f(a1) = f(a2) B ]

Generated subgoal:

1 12. a1 = a2
a1 = a2
3 steps

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