
theorem ord1:
for R being preordered Ring
for P being Preordering of R
for a being Element of R holds a^2 in P
proof
let R be preordered Ring, P be Preordering of R, a be Element of R;
a^2 is square;
then A: a^2 in SQ R;
SQ R c= P by defppc;
hence thesis by A;
end;
