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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">C</font> be    <a href="hidden.html#M1">set</a> ;<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/><b>let </b><font color="Maroon">S</font> be    <a href="relset_1.html#M2">Relation</a> of <font color="Maroon">B</font>,<font color="Maroon">C</font>;<br/>









<b>thus </b><i><font color="Green">E21</font></i>:  <a href="funct_5.html#K2">proj2</a> <span class="p1">(<span class="default"><font color="Maroon">R</font> <a href="relset_2.html#K6" target="_self">*</a> <font color="Maroon">S</font></span>)</span> = 
<span class="p1">(<span class="default"><font color="Maroon">R</font> <a href="relset_2.html#K6" target="_self">*</a> <font color="Maroon">S</font></span>)</span> <a href="relset_1.html#K10">.:</a> <font color="Maroon">A</font>
<b>by </b><i><a class="ref" href="relset_2.html#T3" target="_self">Th3</a></i>
<br/>.= 
<font color="Maroon">S</font> <a href="relset_1.html#K10">.:</a> <span class="p1">(<span class="default"><font color="Maroon">R</font> <a href="relset_1.html#K10">.:</a> <font color="Maroon">A</font></span>)</span>
<b>by </b><i><a class="ref" href="relat_1.html#T159">RELAT_1:159</a></i>
<br/>.= 
<font color="Maroon">S</font> <a href="relset_1.html#K10">.:</a> <span class="p1">(<span class="default"><a href="funct_5.html#K2">proj2</a> <font color="Maroon">R</font></span>)</span>
<b>by </b><i><a class="ref" href="relset_2.html#T3" target="_self">Th3</a></i>
;<br/>

<a NAME="E2:62"/>
 <a href="funct_5.html#K2">proj2</a> <font color="Maroon">R</font> <a href="hidden.html#R1">=</a>  <a href="relset_1.html#K5">rng</a> <font color="Maroon">R</font>
 
<b>by </b><i><a class="ref" href="funct_5.html#T21">FUNCT_5:21</a></i>;<br/>
<a NAME="E3:62"/><b>then </b>
<font color="Maroon">S</font> <a href="relset_1.html#K10">.:</a> <span class="p1">(<span class="default"><a href="funct_5.html#K2">proj2</a> <font color="Maroon">R</font></span>)</span> <a href="tarski.html#R1">c=</a> <font color="Maroon">S</font> <a href="relset_1.html#K10">.:</a> <font color="Maroon">B</font>
 
<b>by </b><i><a class="ref" href="relat_1.html#T156">RELAT_1:156</a></i>;<br/>
<b>hence </b><a NAME="E4:62"/>
 <a href="funct_5.html#K2">proj2</a> <span class="p1">(<span class="default"><font color="Maroon">R</font> <a href="relset_2.html#K6" target="_self">*</a> <font color="Maroon">S</font></span>)</span> <a href="tarski.html#R1">c=</a>  <a href="funct_5.html#K2">proj2</a> <font color="Maroon">S</font>
 <b>by </b><i><a class="ref" href="relset_2.html#T4" target="_self">Th4</a>, <a class="ref" href="relset_2.html#T3" target="_self">Th3</a></i>;<br/>


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