Exercise:

FORALL r(OB(OB)) [FORALL x(OB) EXISTS y(B) r x y IMPLIES EXISTS f(B(OB)) FORALL x r x .f x] IMPLIES EXISTS j(B(OB)) FORALL p(OB) .EXISTS z(B) p z IMPLIES p .j p

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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