Exercise:

EXISTS x(I) R(OII) x x IMPLIES FORALL y(I) R y y IMPLIES EXISTS u(I) FORALL v(I) .R u u IMPLIES R v v

You may not use ADVICE, but all other rules and commands 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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