Exercise:

FORALL s(OA) .~EXISTS g(OAA) FORALL f(OA) .f SUBSET s IMPLIES EXISTS j(A) .s j AND g j = f

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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