reserve i,j,k for Element of NAT;
reserve a,b for Element of REAL;
reserve r,s,t for Element of RAT+;
reserve i,j,k for Element of omega;

theorem Th32:
  REAL <> ExtREAL
proof
  REAL in { REAL, [0,REAL] } by TARSKI:def 2;
  then REAL in ExtREAL by XBOOLE_0:def 3;
  hence thesis;
end;
