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<b>let </b><font color="Maroon">X</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">Y</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">f</font> be   <a href="funct_2.html#NM1">Function</a> of <font color="Maroon">X</font>,<font color="Maroon">Y</font>;<br/>





<b>assume </b><a NAME="E1:97"/><i><font color="Green">E20</font></i>: 
( <font color="Maroon">Y</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a>  implies <font color="Maroon">X</font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a>  )
 ;<br/>

<a NAME="E2:97"/>
<font color="Maroon">f</font> <a href="hidden.html#R1">=</a> <span class="p1"><a href="partfun1.html#K3">&lt;:</a><span class="default"><font color="Maroon">f</font>,<font color="Maroon">X</font>,<font color="Maroon">Y</font></span><a href="partfun1.html#K3">:&gt;</a></span>
 
<b>by </b><i><a class="ref" href="partfun1.html#T87">PARTFUN1:87</a></i>;<br/>
<b>hence </b><a NAME="E3:97"/>
<span class="p1"><a href="partfun1.html#K3">&lt;:</a><span class="default"><font color="Maroon">f</font>,<font color="Maroon">X</font>,<font color="Maroon">Y</font></span><a href="partfun1.html#K3">:&gt;</a></span> is <a href="partfun1.html#V1">total</a>
 <b>by </b><i>, </i>;<br/>


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