rec-exists1

there exists an x for which f(x)=0

W3C sample	WIRIS
[N/A]	$exists x eq f x 0$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <bind>
    <csymbol cd="quant1">exists</csymbol>
    <bvar>
      <ci>x</ci>
    </bvar>
    <apply>
      <csymbol cd="relation1">eq</csymbol>
      <apply>
        <ci>f</ci>
        <ci>x</ci>
      </apply>
      <cn>0</cn>
    </apply>
  </bind>
</math>

Author: MathML 2 Recommendation