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<b>let </b><font color="Maroon">R</font> be   <a href="relat_1.html#NM1">Relation</a>, <font color="Maroon">Q</font> be   <a href="relat_1.html#NM1">Relation</a>;<br/>

<b>assume </b><a NAME="E1:68_2_1"/><i><font color="Green">E29</font></i>: 
for <font color="Olive">a</font>, <font color="Olive">b</font>, <font color="Olive">c</font> being   <a href="hidden.html#M1">set</a>   st <font color="Maroon">R</font> <a href="rewrite1.html#R1" target="_self">reduces</a> <font color="Olive">a</font>,<font color="Olive">b</font> &amp; <font color="Maroon">Q</font> <a href="rewrite1.html#R1" target="_self">reduces</a> <font color="Olive">a</font>,<font color="Olive">c</font> holds <br/> ex <font color="Olive">d</font> being   <a href="hidden.html#M1">set</a>  st <br/>( <font color="Maroon">Q</font> <a href="rewrite1.html#R1" target="_self">reduces</a> <font color="Olive">b</font>,<font color="Olive">d</font> &amp; <font color="Maroon">R</font> <a href="rewrite1.html#R1" target="_self">reduces</a> <font color="Olive">c</font>,<font color="Olive">d</font> )
 ;<br/>

<b>let </b><font color="Maroon">a</font> be    <a href="hidden.html#M1">set</a> , <font color="Maroon">b</font> be    <a href="hidden.html#M1">set</a> , <font color="Maroon">c</font> be    <a href="hidden.html#M1">set</a> ;<br/>

<b>assume </b><a NAME="E2:68_2_1"/>
( <font color="Maroon">Q</font> <a href="rewrite1.html#R1" target="_self">reduces</a> <font color="Maroon">a</font>,<font color="Maroon">b</font> &amp; <font color="Maroon">R</font> <a href="rewrite1.html#R1" target="_self">reduces</a> <font color="Maroon">a</font>,<font color="Maroon">c</font> )
 ;<br/>

<a NAME="E3:68_2_1"/><b>then </b>
 ex <font color="Olive">d</font> being   <a href="hidden.html#M1">set</a>  st <br/>( <font color="Maroon">Q</font> <a href="rewrite1.html#R1" target="_self">reduces</a> <font color="Maroon">c</font>,<font color="Olive">d</font> &amp; <font color="Maroon">R</font> <a href="rewrite1.html#R1" target="_self">reduces</a> <font color="Maroon">b</font>,<font color="Olive">d</font> )
 
<b>by </b><i><a class="ref" href="rewrite1.html#T7" target="_self">Th7</a></i>;<br/>
<b>hence </b><a NAME="E4:68_2_1"/>
 ex <font color="Olive">d</font> being   <a href="hidden.html#M1">set</a>  st <br/>( <font color="Maroon">R</font> <a href="rewrite1.html#R1" target="_self">reduces</a> <font color="Maroon">b</font>,<font color="Olive">d</font> &amp; <font color="Maroon">Q</font> <a href="rewrite1.html#R1" target="_self">reduces</a> <font color="Maroon">c</font>,<font color="Olive">d</font> )
 ;<br/>


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