 reserve x,y,z,t for object,X,Y,Z,W for set;
 reserve R,S,T for Relation;

theorem Th34:
  id dom CL R c= R & id rng CL R c= R
proof
  thus id dom CL R c= R
  proof
    let x,y be object;
    assume [x,y] in id dom CL R;
    then x in dom CL R & x = y by RELAT_1:def 10;
    hence thesis by Th27;
  end;
  hence thesis by Th26;
end;
