
theorem Th7:
  number_e in REAL\NAT
proof
  number_e in REAL & not number_e in RAT by XREAL_0:def 1;
  then number_e in REAL\RAT by XBOOLE_0:def 5;
  hence thesis by NUMBERS:18,XBOOLE_1:34,TARSKI:def 3;
end;
