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<b>take </b>
 <a href="xboole_0.html#K1">{}</a> 
;<br/>

<b>let </b><font color="Maroon">x</font> be    <a href="hidden.html#M1">set</a> ;<br/>

<b>thus </b><a NAME="E1:39_1_1"/>
( <font color="Maroon">x</font> <a href="hidden.html#R2">in</a>  <a href="xboole_0.html#K1">{}</a>  implies <font color="Maroon">x</font> is   <a href="trees_2.html#NM6">DecoratedTree</a> of <font color="Maroon">D</font> )
 ;<br/>


</div>
