let K be non empty right_complementable well-unital add-associative right_zeroed doubleLoopStr ; :: thesis: for J being Function of K,K holds
( J is antiautomorphism iff opp J is isomorphism )
let J be Function of K,K; :: thesis: ( J is antiautomorphism iff opp J is isomorphism )
( J is antiisomorphism iff opp J is isomorphism ) by Th42;
hence ( J is antiautomorphism iff opp J is isomorphism ) by Def17; :: thesis: verum