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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="relset_1.html#M2" target="_self">Relation</a> of <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>1</sub></font>;<br/>





<b>assume </b><a NAME="E1:26"/>
<font color="Maroon">c<sub>3</sub></font> is    <a href="relset_1.html#M2" target="_self">Relation</a> of <font color="Maroon">c<sub>2</sub></font>, <a href="xboole_0.html#K1">{}</a> 
 ;<br/>

<a NAME="E2:26"/><b>then </b>
 <a href="relset_1.html#K5" target="_self">rng</a> <font color="Maroon">c<sub>3</sub></font> <a href="tarski.html#R1">c=</a>  <a href="xboole_0.html#K1">{}</a> 
 
<b>by </b><i><a class="ref" href="relset_1.html#T12" target="_self">Th12</a></i>;<br/>
<a NAME="E3:26"/><b>then </b>
 <a href="relset_1.html#K5" target="_self">rng</a> <font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a> 
 
<b>by </b><i><a class="ref" href="xboole_1.html#T3">XBOOLE_1:3</a></i>;<br/>
<b>hence </b><a NAME="E4:26"/>
<font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a>  <a href="xboole_0.html#K1">{}</a> 
 <b>by </b><i><a class="ref" href="relat_1.html#T64">RELAT_1:64</a></i>;<br/>


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