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<b>defpred </b><font color="Maroon">S<sub>1</sub></font>[   <a href="hidden.html#M1">set</a> ] <b>means </b><font color="Maroon">a<sub>1</sub></font> is  <a href="finset_1.html#V1">finite</a> <a href="trees_1.html#NM1">Tree</a>;<br/>
<b>let </b><font color="Maroon">T1</font> be   <a href="subset_1.html#NM2">Subset</a> of <a href="trees_3.html#K1" target="_self">Trees</a> , <font color="Maroon">T2</font> be   <a href="subset_1.html#NM2">Subset</a> of <a href="trees_3.html#K1" target="_self">Trees</a> ;<br/>

<b>assume </b><b>that </b><br/><a NAME="E1:4_1_2"/><i><font color="Green">E39</font></i>: 
for <font color="Olive">x</font> being   <a href="hidden.html#M1">set</a>  holds <br/> ( <font color="Olive">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">T1</font> iff <font color="Maroon">S<sub>1</sub></font>[<font color="Olive">x</font>] )
 <b>and </b><br/><a NAME="E2:4_1_2"/><i><font color="Green">E40</font></i>: 
for <font color="Olive">x</font> being   <a href="hidden.html#M1">set</a>  holds <br/> ( <font color="Olive">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">T2</font> iff <font color="Maroon">S<sub>1</sub></font>[<font color="Olive">x</font>] )
 ;<br/>

<b>thus </b><a NAME="E3:4_1_2"/>
<font color="Maroon">T1</font> <a href="hidden.html#R1">=</a> <font color="Maroon">T2</font>
 <b>from </b><i><a class="ref" href="xboole_0.html#S2">XBOOLE_0:sch 2</a>(, );</i><br/>


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