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<b>let </b><font color="Maroon">C</font> be   <a href="coh_sp.html#NM1">Coherence_Space</a>;<br/>

<b>assume </b><a NAME="E1:13"/><i><font color="Green">E17</font></i>: 
 <a href="tarski.html#K3">union</a> <font color="Maroon">C</font> <a href="hidden.html#R2">in</a> <font color="Maroon">C</font>
 ;<br/>

<b>thus </b><a NAME="E2:13"/>
<font color="Maroon">C</font> <a href="tarski.html#R1">c=</a>  <a href="zfmisc_1.html#K1">bool</a> <span class="p1">(<span class="default"><a href="tarski.html#K3">union</a> <font color="Maroon">C</font></span>)</span>
 <b>by </b><i><a class="ref" href="zfmisc_1.html#T100">ZFMISC_1:100</a></i>; <i><font color="Red">:: according to </font></i><a class="ref" href="xboole_0.html#D10">XBOOLE_0:def 10</a><br/>

<b>let </b><font color="Maroon">x</font> be    <a href="hidden.html#M1">set</a> ; <i><font color="Red">:: according to </font></i><a class="ref" href="tarski.html#D3">TARSKI:def 3</a><br/>

<b>assume </b><a NAME="E3:13"/>
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a>  <a href="zfmisc_1.html#K1">bool</a> <span class="p1">(<span class="default"><a href="tarski.html#K3">union</a> <font color="Maroon">C</font></span>)</span>
 ;<br/>

<b>hence </b><a NAME="E4:13"/>
<font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">C</font>
 <b>by </b><i>, <a class="ref" href="classes1.html#D1">CLASSES1:def 1</a></i>;<br/>


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