Example exc-154

Prev: exc-153

Next: exc-155

x a b f x

<math>
<apply><sum/>
  <bvar> <ci> x </ci></bvar>
  <lowlimit><ci> a </ci></lowlimit>
  <uplimit><ci> b </ci></uplimit>
  <apply><ci> f </ci><ci> x </ci></apply>
</apply>
</math>