reserve x,y,z for object,X,Y for set;
reserve N for e_net;

theorem Th3:
  G_Net (# X, id X, id X #) is e_net
proof
A1: id(X) * (id(X) \ id(X)) = id(X) * {} by XBOOLE_1:37
    .= {};
  id(X) c= [:X, X:] & id(X) * id(X) = id(X) by RELSET_1:13,SYSREL:12;
  hence thesis by A1,Def1,Def2;
end;
