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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> ex <font color="Olive">T</font> being  <a href="trees_2.html#NM6">DecoratedTree</a> of <font color="Maroon">D</font> st <br/>( <font color="Maroon">a<sub>1</sub></font> <a href="hidden.html#R1">=</a> <font color="Olive">T</font> &amp;  <a href="relat_1.html#K1">dom</a> <font color="Olive">T</font> is <a href="finset_1.html#V1">finite</a> );<br/>
<b>consider </b><font color="Maroon">X</font> being    <a href="hidden.html#M1">set</a> <b> such that </b><br/><a NAME="E2:47_1_1"/><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">X</font> iff ( <font color="Olive">x</font> <a href="hidden.html#R2">in</a>  <a href="trees_3.html#K4" target="_self">Trees</a> <font color="Maroon">D</font> &amp; <font color="Maroon">S<sub>1</sub></font>[<font color="Olive">x</font>] ) )
 <b>from </b><i><a class="ref" href="xboole_0.html#S1">XBOOLE_0:sch 1</a>();<br/></i>
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="47_1_1_1"><b>now </b></a><div class="add"><b>let </b><font color="Maroon">x</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>assume </b><a NAME="E1:47_1_1_1"/>
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font>
 ;<br/><a NAME="E2:47_1_1_1"/><b>then </b>
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a>  <a href="trees_3.html#K4" target="_self">Trees</a> <font color="Maroon">D</font>
 <b>by </b><i/>;<br/><b>hence </b><a NAME="E3:47_1_1_1"/>
<font color="Maroon">x</font> is   <a href="trees_2.html#NM6">DecoratedTree</a> of <font color="Maroon">D</font>
 <b>by </b><i/>;<br/></div><b>end;</b></div>
<b>then reconsider </b><font color="Maroon">X</font> = <font color="Maroon">X</font> as    <a href="trees_3.html#M4" target="_self">DTree-set</a> of <font color="Maroon">D</font> <b>by </b><i/>;<br/>
<b>take </b>
<font color="Maroon">X</font>
;<br/>

<b>let </b><font color="Maroon">T</font> be   <a href="trees_2.html#NM6">DecoratedTree</a> of <font color="Maroon">D</font>;<br/>

<a NAME="E5:47_1_1"/>
<font color="Maroon">T</font> <a href="hidden.html#R2">in</a>  <a href="trees_3.html#K4" target="_self">Trees</a> <font color="Maroon">D</font>
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E6:47_1_1"/>
(  <a href="relat_1.html#K1">dom</a> <font color="Maroon">T</font> is <a href="finset_1.html#V1">finite</a> implies <font color="Maroon">T</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font> )
 <b>by </b><i/>;<br/>

<b>assume </b><a NAME="E7:47_1_1"/>
<font color="Maroon">T</font> <a href="hidden.html#R2">in</a> <font color="Maroon">X</font>
 ;<br/>

<a NAME="E8:47_1_1"/><b>then </b>
 ex <font color="Olive">t</font> being  <a href="trees_2.html#NM6">DecoratedTree</a> of <font color="Maroon">D</font> st <br/>( <font color="Maroon">T</font> <a href="hidden.html#R1">=</a> <font color="Olive">t</font> &amp;  <a href="relat_1.html#K1">dom</a> <font color="Olive">t</font> is <a href="finset_1.html#V1">finite</a> )
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E9:47_1_1"/>
 <a href="relat_1.html#K1">dom</a> <font color="Maroon">T</font> is <a href="finset_1.html#V1">finite</a>
 ;<br/>


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