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<a NAME="E1:65_1_1"/>
 <a href="afinsq_1.html#K1" title="AFINSQ_1:func.1">len</a> <span class="p1">(<span class="default"><a href="afinsq_2.html#K10" title="AFINSQ_2:func.10">SubXFinS</a> <font color="Maroon" title="c1">f</font>,<a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a> </span>)</span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="card_1.html#K5" title="CARD_1:func.5">card</a> <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a> 
 
<b>by </b><i><a class="ref" href="afinsq_2.html#T47" target="_self" title="AFINSQ_2:th.47">AC200</a></i>;<br/>
<b>hence </b><a NAME="E2:65_1_1"/>
 <a href="afinsq_2.html#K10" title="AFINSQ_2:func.10">SubXFinS</a> <font color="Maroon" title="c1">f</font>,<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>
 ; <a class="txt" onclick="hs(this)" href="javascript:()"><i><font color="Red">::  thesis: </font></i></a><span class="hide"> verum</span><br/>


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