reserve R,R1 for commutative Ring;
reserve A,B for non degenerated commutative Ring;
reserve o,o1,o2 for object;
reserve r,r1,r2 for Element of R;
reserve a,a1,a2,b,b1 for Element of A;
reserve f for Function of R, R1;
reserve p for Element of Spectrum A;

theorem Th3:
  not 0.A in Non_ZeroDiv_Set(A)
  proof
    0.A is Zero_Divisor of A by Th1; then
    0.A in ZeroDiv_Set(A);
    hence thesis by XBOOLE_0:def 5;
  end;
