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<div><span class="kw">theorem </span><a NAME="T7"><span class="comment"><font color="firebrick">:: HILBERT3:7</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">x</font> being    <a href="hidden.html#M2" title="HIDDEN:mode.2">set</a>  holds  <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a> <a href="funct_1.html#K1" title="FUNCT_1:func.1">.</a> <font color="Olive" title="b1">x</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a>  ;<br/></div></div>
