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<b>let </b><font color="Maroon">i1</font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">I</font>, <font color="Maroon">i2</font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">I</font>;<br/>

<b>assume </b><a NAME="E1:43_1_2"/><i><font color="Green">E38</font></i>: 
( not <font color="Maroon">B</font> <a href="funct_1.html#K1">.</a> <font color="Maroon">i1</font> is <a href="realset1.html#V1">trivial</a> &amp; not <font color="Maroon">B</font> <a href="funct_1.html#K1">.</a> <font color="Maroon">i2</font> is <a href="realset1.html#V1">trivial</a> )
 ;<br/>

<b>consider </b><font color="Maroon">i</font> being    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">I</font><b> such that </b><br/><a NAME="E3:43_1_2"/><i><font color="Green">E49</font></i>: 
for <font color="Olive">j</font> being   <a href="subset_1.html#M1">Element</a> of <font color="Maroon">I</font>  st <font color="Maroon">i</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Olive">j</font> holds <br/>( not <font color="Maroon">B</font> <a href="funct_1.html#K1">.</a> <font color="Olive">j</font> is <a href="xboole_0.html#V1">empty</a> &amp; <font color="Maroon">B</font> <a href="funct_1.html#K1">.</a> <font color="Olive">j</font> is <a href="realset1.html#V1">trivial</a> )
 <b>by </b><i/>;<br/>
<b>thus </b><font color="Maroon">i1</font> = 
<font color="Maroon">i</font>
<b>by </b><i>, </i>
<br/>.= 
<font color="Maroon">i2</font>
<b>by </b><i>, </i>
;<br/>


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