reserve M,N for AbGroup;
 reserve R for Ring;
 reserve r for Element of R;

theorem Tref:
   for M be LeftMod of R holds M ~= M
   proof
    let M be LeftMod of R;
A1: id M is Endomorphism of R,M by Def10;
    id M is onto by RELAT_1:45;
    hence thesis by A1;
   end;
