
<!DOCTYPE math
  PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<math xmlns="http://www.w3.org/1998/Math/MathML">
<apply>
  <int/>
  <bvar><ci> x </ci></bvar>
  <condition>
    <apply><in/><ci> x </ci><ci> D </ci></apply>
  </condition>
  <apply><ci type="fn"> f </ci>
    <ci> x </ci>
  </apply>
</apply>
</math>
