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<b>let </b><font color="Maroon" title="c3">X</font>, <font color="Maroon" title="c4">Y</font> be   <a href="ideal_1.html#NM3" title="IDEAL_1:NM.3">LeftIdeal</a> of <font color="Maroon" title="c1">L</font>;<br/>

<b>assume </b><b>that </b><br/><a NAME="E1:75_2_2"/><i><font color="Green" title="E36">A39</font></i>: 
( <font color="Maroon" title="c2">F</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a> <font color="Maroon" title="c3">X</font> &amp; ( for <font color="Olive" title="b1">I</font> being  <a href="ideal_1.html#NM3" title="IDEAL_1:NM.3">LeftIdeal</a> of <font color="Maroon" title="c1">L</font>  st <font color="Maroon" title="c2">F</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a> <font color="Olive" title="b1">I</font> holds <br/><font color="Maroon" title="c3">X</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a> <font color="Olive" title="b1">I</font> ) )
 <b>and </b><br/><a NAME="E2:75_2_2"/><i><font color="Green" title="E37">A40</font></i>: 
( <font color="Maroon" title="c2">F</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a> <font color="Maroon" title="c4">Y</font> &amp; ( for <font color="Olive" title="b1">I</font> being  <a href="ideal_1.html#NM3" title="IDEAL_1:NM.3">LeftIdeal</a> of <font color="Maroon" title="c1">L</font>  st <font color="Maroon" title="c2">F</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a> <font color="Olive" title="b1">I</font> holds <br/><font color="Maroon" title="c4">Y</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a> <font color="Olive" title="b1">I</font> ) )
 ;<br/>

<a NAME="E3:75_2_2"/><i><font color="Green" title="E38">A41</font></i>: 
<font color="Maroon" title="c3">X</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a> <font color="Maroon" title="c4">Y</font>
 
<b>by </b><i><a class="txt" href="ideal_1.html#E1:75_2_2"><i><font color="Green" title="E36">A39</font></i></a>, <a class="txt" href="ideal_1.html#E2:75_2_2"><i><font color="Green" title="E37">A40</font></i></a></i>;<br/>
<a NAME="E4:75_2_2"/>
<font color="Maroon" title="c4">Y</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a> <font color="Maroon" title="c3">X</font>
 
<b>by </b><i><a class="txt" href="ideal_1.html#E1:75_2_2"><i><font color="Green" title="E36">A39</font></i></a>, <a class="txt" href="ideal_1.html#E2:75_2_2"><i><font color="Green" title="E37">A40</font></i></a></i>;<br/>
<b>hence </b><a NAME="E5:75_2_2"/>
<font color="Maroon" title="c3">X</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> <font color="Maroon" title="c4">Y</font>
 <b>by </b><i><a class="txt" href="ideal_1.html#E3:75_2_2"><i><font color="Green" title="E38">A41</font></i></a>, <a class="ref" href="xboole_0.html#D10" title="XBOOLE_0:def.10">XBOOLE_0:def 10</a></i>;<br/>


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