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<div><span class="kw">theorem </span><a NAME="T3"><span class="comment"><font color="firebrick">:: GATE_1:3</font></span><br/></a><div class="add"> not  <a href="gate_1.html#K1" title="GATE_1:func.1">NOT1</a> <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a> is  <a href="xboole_0.html#V1" title="XBOOLE_0:attr.1">empty</a>  ;<br/></div></div>
