A1: now
assume j <> {} ; :: thesis: ( RED (j,i) <> 1 implies [(RED (i,j)),(RED (j,i))] in RAT+ )
then ( RED (i,j), RED (j,i) are_relative_prime & RED (j,i) <> {} ) by Th23, Th24;
hence ( RED (j,i) <> 1 implies [(RED (i,j)),(RED (j,i))] in RAT+ ) by Th39; :: thesis: verum
end;
RED (i,j) in omega ;
hence ( ( j = {} implies {} is Element of RAT+ ) & ( RED (j,i) = 1 implies RED (i,j) is Element of RAT+ ) & ( not j = {} & not RED (j,i) = 1 implies [(RED (i,j)),(RED (j,i))] is Element of RAT+ ) ) by A1, Lm1, Lm5; :: thesis: verum