a in A
<math xmlns="http://www.w3.org/1998/Math/MathML"> <apply> <csymbol cd="set1">in</csymbol> <ci>a</ci> <semantics> <ci>A</ci> <annotation-xml cd="mathmltypes" name="type" encoding="MathML-Content"> <ci>set</ci> </annotation-xml> </semantics> </apply> </math>
Author: MathML 2 Recommendation