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<b>let </b><font color="Maroon">A</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">B</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">X</font> be   <a href="subset_1.html#NM2">Subset</a> of <font color="Maroon">A</font>;<br/><b>let </b><font color="Maroon">Y</font> be   <a href="subset_1.html#NM2">Subset</a> of <font color="Maroon">B</font>;<br/><b>let </b><font color="Maroon">R</font> be    <a href="relset_1.html#M2">Relation</a> of <font color="Maroon">A</font>,<font color="Maroon">B</font>;<br/>









<a NAME="E1:70"/>
( <font color="Maroon">X</font> <a href="subset_1.html#K3">`</a>  <a href="xboole_0.html#R1">misses</a> <span class="p1">(<span class="default"><font color="Maroon">R</font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_1.html#K10">.:</a> <font color="Maroon">Y</font> iff <font color="Maroon">Y</font> <a href="xboole_0.html#R1">misses</a> <font color="Maroon">R</font> <a href="relset_1.html#K10">.:</a> <span class="p1">(<span class="default"><font color="Maroon">X</font> <a href="subset_1.html#K3">`</a> </span>)</span> )
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E2:70"/>
( <font color="Maroon">R</font> <a href="relset_1.html#K10">.:</a> <span class="p1">(<span class="default"><font color="Maroon">X</font> <a href="subset_1.html#K3">`</a> </span>)</span> <a href="tarski.html#R1">c=</a> <font color="Maroon">Y</font> <a href="subset_1.html#K3">`</a>  iff <span class="p1">(<span class="default"><font color="Maroon">R</font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_1.html#K10">.:</a> <font color="Maroon">Y</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">X</font> )
 <b>by </b><i><a class="ref" href="subset_1.html#T44">SUBSET_1:44</a>, <a class="ref" href="subset_1.html#T43">SUBSET_1:43</a></i>;<br/>


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