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<b>let </b><font color="Maroon" title="c3">SF</font> be   <a href="mssubfam.html#NM1" title="MSSUBFAM:NM.1">MSSubsetFamily</a> of <font color="Maroon" title="c2">M</font>;<br/>

<b>assume </b><a NAME="E1:86_1_1"/>
<font color="Maroon" title="c3">SF</font> is <a href="mssubfam.html#V6" title="MSSUBFAM:attr.6">properly-lower-bound</a>
 ;<br/>

<a NAME="E2:86_1_1"/><b>then </b><i><font color="Green" title="E20">A1</font></i>: 
 <a href="pboole.html#K1" title="PBOOLE:func.1">[0]</a> <font color="Maroon" title="c1">I</font> <a href="pboole.html#R1" title="PBOOLE:pred.1">in</a> <font color="Maroon" title="c3">SF</font>
 
<b>by </b><i><a class="ref" href="mssubfam.html#D8" target="_self" title="MSSUBFAM:def.8">Def8</a></i>;<br/>
<b>let </b><font color="Maroon" title="c4">i</font> be    <a href="hidden.html#M1" title="HIDDEN:mode.1">set</a> ; <i><font color="Red">:: according to </font></i><a class="ref" href="pboole.html#D16" title="PBOOLE:def.16">PBOOLE:def 16</a><br/>

<b>assume </b><a NAME="E3:86_1_1"/>
<font color="Maroon" title="c4">i</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c1">I</font>
 ;<br/>

<b>hence </b><a NAME="E4:86_1_1"/>
not <font color="Maroon" title="c3">SF</font> <a href="funct_1.html#K1" title="FUNCT_1:func.1">.</a> <font color="Maroon" title="c4">i</font> is <a href="xboole_0.html#V1" title="XBOOLE_0:attr.1">empty</a>
 <b>by </b><i><a class="txt" href="mssubfam.html#E2:86_1_1"><i><font color="Green" title="E20">A1</font></i></a>, <a class="ref" href="pboole.html#D4" title="PBOOLE:def.4">PBOOLE:def 4</a></i>;<br/>


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