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<b>let </b><font color="Maroon">X</font> be   <a href="ideal_1.html#NM2">RightIdeal</a> of <font color="Maroon">L</font>, <font color="Maroon">Y</font> be   <a href="ideal_1.html#NM2">RightIdeal</a> of <font color="Maroon">L</font>;<br/>

<b>assume </b><b>that </b><br/><a NAME="E1:75_3_2"/><i><font color="Green">E167</font></i>: 
( <font color="Maroon">F</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">X</font> &amp; ( for <font color="Olive">I</font> being  <a href="ideal_1.html#NM2">RightIdeal</a> of <font color="Maroon">L</font>  st <font color="Maroon">F</font> <a href="tarski.html#R1">c=</a> <font color="Olive">I</font> holds <br/><font color="Maroon">X</font> <a href="tarski.html#R1">c=</a> <font color="Olive">I</font> ) )
 <b>and </b><br/><a NAME="E2:75_3_2"/><i><font color="Green">E168</font></i>: 
( <font color="Maroon">F</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">Y</font> &amp; ( for <font color="Olive">I</font> being  <a href="ideal_1.html#NM2">RightIdeal</a> of <font color="Maroon">L</font>  st <font color="Maroon">F</font> <a href="tarski.html#R1">c=</a> <font color="Olive">I</font> holds <br/><font color="Maroon">Y</font> <a href="tarski.html#R1">c=</a> <font color="Olive">I</font> ) )
 ;<br/>

<a NAME="E3:75_3_2"/><i><font color="Green">E169</font></i>: 
<font color="Maroon">X</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">Y</font>
 
<b>by </b><i>, <a class="ref" href="ideal_1.html#D2" target="_self">Def2</a></i>;<br/>
<a NAME="E4:75_3_2"/>
<font color="Maroon">Y</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">X</font>
 
<b>by </b><i>, <a class="ref" href="ideal_1.html#D2" target="_self">Def2</a></i>;<br/>
<b>hence </b><a NAME="E5:75_3_2"/>
<font color="Maroon">X</font> <a href="hidden.html#R1">=</a> <font color="Maroon">Y</font>
 <b>by </b><i>, <a class="ref" href="xboole_0.html#D10">XBOOLE_0:def 10</a></i>;<br/>


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