1<math xmlns='http://www.w3c.org/mathml' version='2.0'> 2 <apply> <eq/> 3 <apply> <diff/> 4 <bvar> <ci> x </ci> </bvar> 5 <ci> a </ci> 6 </apply> 7 <ci> 0 </ci> 8 </apply> 9</math>