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<b>let </b><font color="Maroon">W</font> be   <a href="classes2.html#NM1">Universe</a>;<br/>

<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="4_1"><b>now </b></a><div class="add"><b>let </b><font color="Maroon">u</font> be    <a href="subset_1.html#M1">Element</a> of <font color="Maroon">W</font>;<br/><a NAME="E1:4_1"/>
(  <a href="classes2.html#K2">bool</a> <font color="Maroon">u</font> <a href="hidden.html#R2">in</a> <font color="Maroon">W</font> &amp; <font color="Maroon">W</font> <a href="xboole_0.html#K3">/\</a> <span class="p1">(<span class="default"><a href="classes2.html#K2">bool</a> <font color="Maroon">u</font></span>)</span> <a href="tarski.html#R1">c=</a>  <a href="classes2.html#K2">bool</a> <font color="Maroon">u</font> )
 <b>by </b><i><a class="ref" href="xboole_1.html#T17">XBOOLE_1:17</a></i>;<br/><b>hence </b><a NAME="E2:4_1"/>
<font color="Maroon">W</font> <a href="xboole_0.html#K3">/\</a> <span class="p1">(<span class="default"><a href="classes2.html#K2">bool</a> <font color="Maroon">u</font></span>)</span> <a href="hidden.html#R2">in</a> <font color="Maroon">W</font>
 <b>by </b><i><a class="ref" href="classes1.html#D1">CLASSES1:def 1</a></i>;<br/></div><b>end;</b></div>
<b>hence </b><a NAME="E2:4"/>
<font color="Maroon">W</font> <a href="zf_model.html#R2">|=</a>  <a href="zf_model.html#K10">the_axiom_of_power_sets</a> 
 <b>by </b><i><a class="ref" href="zfmodel1.html#T8">ZFMODEL1:8</a></i>;<br/>


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