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

theorem Th32:
  dom CL R c= dom R & rng CL R c= rng R & rng CL R c= dom R & dom CL R c= rng R
proof
  CL R c= R by XBOOLE_1:17;
  hence dom CL R c= dom R & rng CL R c= rng R by RELAT_1:11;
  hence thesis by Th26;
end;
