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<b>let </b><font color="Maroon">x</font> be    <a href="trees_3.html#M3">Element</a> of <font color="Maroon">Tset</font>;<br/>

<a NAME="E1:5_1_1"/>
( <font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">Tset</font> &amp; <font color="Maroon">Tset</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">F</font> )
 
;<br/>
<b>hence </b><a NAME="E2:5_1_1"/>
<font color="Maroon">x</font> is    <a href="trees_3.html#M5">Element</a> of <font color="Maroon">F</font>
 ;<br/>


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