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

<div><b>hereby </b>
<div class="add"><b>assume </b><a NAME="E1:75_1"/><i><font color="Green">E21</font></i>: 
<font color="Maroon">R</font> is <a href="rewrite1.html#V9" target="_self">locally-confluent</a>
 ;<br/><b>thus </b><a NAME="E2:75_1"/>
<font color="Maroon">R</font> <a href="rewrite1.html#R10" target="_self">commutes-weakly_with</a> <font color="Maroon">R</font>
 <div><a class="txt" onclick="hs2(this)" href="javascript:()" title="75_1_1"><b>proof </b></a><div class="add">

<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> ; <i><font color="Red">:: according to </font></i><a class="ref" href="rewrite1.html#D17" target="_self">REWRITE1:def 17</a><br/>

<b>assume </b><a NAME="E1:75_1_1"/>
( <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font></span><a href="tarski.html#K4">]</a></span> <a href="hidden.html#R2">in</a> <font color="Maroon">R</font> &amp; <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Maroon">a</font>,<font color="Maroon">c</font></span><a href="tarski.html#K4">]</a></span> <a href="hidden.html#R2">in</a> <font color="Maroon">R</font> )
 ;<br/>

<a NAME="E2:75_1_1"/><b>then </b>
<font color="Maroon">b</font>,<font color="Maroon">c</font> <a href="rewrite1.html#R5" target="_self">are_convergent_wrt</a> <font color="Maroon">R</font>
 
<b>by </b><i><a class="ref" href="rewrite1.html#D3" target="_self">Def3</a>, <a class="ref" href="rewrite1.html#T10" target="_self">Th10</a></i>;<br/>
<b>hence </b><a NAME="E3:75_1_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">R</font> <a href="rewrite1.html#R1" target="_self">reduces</a> <font color="Maroon">c</font>,<font color="Olive">d</font> )
 <b>by </b><i/>;<br/>


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

<b>assume </b><a NAME="E2:75"/><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 <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Olive">a</font>,<font color="Olive">b</font></span><a href="tarski.html#K4">]</a></span> <a href="hidden.html#R2">in</a> <font color="Maroon">R</font> &amp; <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Olive">a</font>,<font color="Olive">c</font></span><a href="tarski.html#K4">]</a></span> <a href="hidden.html#R2">in</a> <font color="Maroon">R</font> holds <br/> 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="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> )
 ; <i><font color="Red">:: according to </font></i><a class="ref" href="rewrite1.html#D17" target="_self">REWRITE1:def 17</a><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> ; <i><font color="Red">:: according to </font></i><a class="ref" href="rewrite1.html#D24" target="_self">REWRITE1:def 24</a><br/>

<b>assume </b><a NAME="E3:75"/>
( <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Maroon">a</font>,<font color="Maroon">b</font></span><a href="tarski.html#K4">]</a></span> <a href="hidden.html#R2">in</a> <font color="Maroon">R</font> &amp; <span class="p1"><a href="tarski.html#K4">[</a><span class="default"><font color="Maroon">a</font>,<font color="Maroon">c</font></span><a href="tarski.html#K4">]</a></span> <a href="hidden.html#R2">in</a> <font color="Maroon">R</font> )
 ;<br/>

<b>hence </b><a NAME="E4:75"/>
 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">R</font> <a href="rewrite1.html#R1" target="_self">reduces</a> <font color="Maroon">c</font>,<font color="Olive">d</font> )
 <b>by </b><i><a class="ref" href="rewrite1.html#D3" target="_self">Def3</a></i>; <i><font color="Red">:: according to </font></i><a class="ref" href="rewrite1.html#D7" target="_self">REWRITE1:def 7</a><br/>


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