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<b>let </b><font color="Maroon">I</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">sf</font> be   <a href="setfam_1.html#NM1">Subset-Family</a> of <font color="Maroon">I</font>;<br/>



<b>assume </b><a NAME="E1:5"/><i><font color="Green">E36</font></i>: 
 <a href="xboole_0.html#K1">{}</a>  <a href="hidden.html#R2">in</a> <font color="Maroon">sf</font>
 ;<br/>

<a NAME="E2:5"/><b>then </b>
 <a href="setfam_1.html#K8">Intersect</a> <font color="Maroon">sf</font> <a href="hidden.html#R1">=</a>  <a href="setfam_1.html#K6">meet</a> <font color="Maroon">sf</font>
 
<b>by </b><i><a class="ref" href="setfam_1.html#D10">SETFAM_1:def 10</a></i>;<br/>
<b>hence </b><a NAME="E3:5"/>
 <a href="setfam_1.html#K8">Intersect</a> <font color="Maroon">sf</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a> 
 <b>by </b><i>, <a class="ref" href="setfam_1.html#T5">SETFAM_1:5</a></i>;<br/>


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