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<b>let </b><font color="Maroon">c<sub>1</sub></font>, <font color="Maroon">c<sub>2</sub></font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">c<sub>3</sub></font> be   <a href="subset_1.html#NM2">Subset</a> of <font color="Maroon">c<sub>1</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>4</sub></font> be   <a href="subset_1.html#NM2">Subset</a> of <font color="Maroon">c<sub>2</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>5</sub></font> be    <a href="relset_1.html#M2">Relation</a> of <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font>;<br/>









<b>thus </b><a NAME="E1:71"/>
<font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_2.html#K5" target="_self">.:^</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <font color="Maroon">c<sub>3</sub></font></span>)</span></span>)</span>
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="71_1"><b>proof </b></a><div class="add">

<b>thus </b><a NAME="E1:71_1"/>
<font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <font color="Maroon">c<sub>3</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_2.html#K5" target="_self">.:^</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <font color="Maroon">c<sub>3</sub></font></span>)</span></span>)</span>
 <b>by </b><i><a class="ref" href="relset_2.html#T61" target="_self">Th61</a></i>; <i><font color="Red">:: according to </font></i><a class="ref" href="xboole_0.html#D10">XBOOLE_0:def 10</a><br/>

<a NAME="E2:71_1"/>
<font color="Maroon">c<sub>3</sub></font> <a href="tarski.html#R1">c=</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_2.html#K5" target="_self">.:^</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <font color="Maroon">c<sub>3</sub></font></span>)</span>
 
<b>by </b><i><a class="ref" href="relset_2.html#T61" target="_self">Th61</a></i>;<br/>
<b>hence </b><a NAME="E3:71_1"/>
<font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_2.html#K5" target="_self">.:^</a> <span class="p2">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <font color="Maroon">c<sub>3</sub></font></span>)</span></span>)</span> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <font color="Maroon">c<sub>3</sub></font>
 <b>by </b><i><a class="ref" href="relset_2.html#T32" target="_self">Th32</a></i>;<br/>


</div><b>end;</b></div>

<b>thus </b><a NAME="E2:71"/>
<span class="p1">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_2.html#K5" target="_self">.:^</a> <font color="Maroon">c<sub>4</sub></font> <a href="tarski.html#R1">c=</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_2.html#K5" target="_self">.:^</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <span class="p2">(<span class="default"><span class="p3">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_2.html#K5" target="_self">.:^</a> <font color="Maroon">c<sub>4</sub></font></span>)</span></span>)</span>
 <b>by </b><i><a class="ref" href="relset_2.html#T61" target="_self">Th61</a></i>; <i><font color="Red">:: according to </font></i><a class="ref" href="xboole_0.html#D10">XBOOLE_0:def 10</a><br/>

<a NAME="E3:71"/>
<font color="Maroon">c<sub>4</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_2.html#K5" target="_self">.:^</a> <font color="Maroon">c<sub>4</sub></font></span>)</span>
 
<b>by </b><i><a class="ref" href="relset_2.html#T61" target="_self">Th61</a></i>;<br/>
<b>hence </b><a NAME="E4:71"/>
<span class="p1">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_2.html#K5" target="_self">.:^</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_2.html#K5" target="_self">.:^</a> <span class="p2">(<span class="default"><span class="p3">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_2.html#K5" target="_self">.:^</a> <font color="Maroon">c<sub>4</sub></font></span>)</span></span>)</span> <a href="tarski.html#R1">c=</a> <span class="p1">(<span class="default"><font color="Maroon">c<sub>5</sub></font> <a href="relset_1.html#K6">~</a> </span>)</span> <a href="relset_2.html#K5" target="_self">.:^</a> <font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="ref" href="relset_2.html#T32" target="_self">Th32</a></i>;<br/>


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