Suppose you want some MathML like this:
<?xml version="1.0" encoding="UTF-8"?>
<math xmlns="http://www.w3.org/1998/Math/MathML">
<mrow>
<mi>f(0)</mi>
<mo>=</mo>
<mn>0</mn>
</mrow>
<mrow>
<mi>f(1)</mi>
<mo>=</mo>
<mn>1</mn>
</mrow>
<mrow>
<mi>f(2)</mi>
<mo>=</mo>
<mn>1</mn>
</mrow>
</math>
Do not use the local names like mn.
Instead use the local names like mn,
and URIs like http://www.w3.org/1998/Math/MathML
to create the elements.
Do not include xmlns attributes
like xmlns="http://www.w3.org/1998/Math/MathML".
XMLOutputter will
decide where to put the xmlns attribute
when the document is serialized.