rec-inverse3

W3C sample WIRIS
a A
<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <apply>
      <inverse/>
      <ci type="matrix">a</ci>
    </apply>
    <ci>A</ci>
  </apply>
</math>

Author: MathML 2 Recommendation