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<a NAME="E1:27_1_1"/>
 <a href="pboole.html#K11">MSFuncs</a> <font color="Maroon">A</font>,<font color="Maroon">B</font> is <a href="relat_1.html#V2">non-empty</a>
 
<b>by </b><i>, </i>;<br/>
<a NAME="E2:27_1_1"/><b>then </b>
not  <a href="xboole_0.html#K1">{}</a>  <a href="hidden.html#R2">in</a>  <a href="relat_1.html#K2">rng</a> <span class="p1">(<span class="default"><a href="pboole.html#K11">MSFuncs</a> <font color="Maroon">A</font>,<font color="Maroon">B</font></span>)</span>
 
<b>by </b><i><a class="ref" href="pboole.html#T149">PBOOLE:149</a></i>;<br/>
<b>then reconsider </b><font color="Maroon">X</font> =  <a href="card_3.html#K4">product</a> <span class="p1">(<span class="default"><a href="pboole.html#K11">MSFuncs</a> <font color="Maroon">A</font>,<font color="Maroon">B</font></span>)</span> as  non <a href="xboole_0.html#V1">empty</a>  <a href="hidden.html#M1">set</a>  <b>by </b><i><a class="ref" href="card_3.html#T37">CARD_3:37</a></i>;<br/>
<b>take </b>
<font color="Maroon">X</font>
;<br/>

<b>let </b><font color="Maroon">x</font> be    <a href="hidden.html#M1">set</a> ;<br/>

<b>assume </b><a NAME="E4:27_1_1"/>
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font>
 ;<br/>

<b>hence </b><a NAME="E5:27_1_1"/>
<font color="Maroon">x</font> is    <a href="pboole.html#M3">ManySortedFunction</a> of <font color="Maroon">A</font>,<font color="Maroon">B</font>
 <b>by </b><i>, </i>;<br/>


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