Exercise:

FORALL P(OB) [EXISTS x(B) P x IMPLIES P .J(B(OB)) P] IMPLIES FORALL f(AB) FORALL g(AB) .f [J .LAMBDA x .~.f x = g x] = g [J .LAMBDA x .~.f x = g x] IMPLIES f = g

All rules and commands, including ADVICE, are allowed.

Only book theorems may be ASSERTed as lemmas without proof.

For a complete list of book theorems, type PROBLEMS.

No more help available. Sorry.

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