min(x, x not in B, x^2) using <reln>
<math xmlns="http://www.w3.org/1998/Math/MathML">
<apply>
<min/>
<bvar>
<ci>x</ci>
</bvar>
<condition>
<reln>
<notin/>
<ci>x</ci>
<ci type="set">B</ci>
</reln>
</condition>
<apply>
<power/>
<ci>x</ci>
<cn>2</cn>
</apply>
</apply>
</math>
Author: Design Science, Inc. (E. Cannon, E. Tabacman, R.Miner)