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<b>let </b><font color="Maroon">X</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">S</font> be   <a href="prob_1.html#NM3">SigmaField</a> of <font color="Maroon">X</font>;<br/><b>let </b><font color="Maroon">F</font> be   <a href="funct_2.html#NM1">Function</a> of  <a href="numbers.html#K5">NAT</a> ,<font color="Maroon">S</font>;<br/>





<a NAME="E1:52"/><i><font color="Green">E21</font></i>: 
 <a href="measure1.html#K5" target="_self">rng</a> <font color="Maroon">F</font> is   <a href="measure1.html#NM3">N_Sub_set_fam</a> of <font color="Maroon">X</font>
 
<b>by </b><i/>;<br/>
<a NAME="E2:52"/>
 <a href="measure1.html#K5" target="_self">rng</a> <font color="Maroon">F</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">S</font>
 
<b>by </b><i><a class="ref" href="relset_1.html#T12">RELSET_1:12</a></i>;<br/>
<b>hence </b><a NAME="E3:52"/>
 <a href="setfam_1.html#K5">union</a> <span class="p1">(<span class="default"><a href="measure1.html#K5" target="_self">rng</a> <font color="Maroon">F</font></span>)</span> is    <a href="subset_1.html#M2">Element</a> of <font color="Maroon">S</font>
 <b>by </b><i>, </i>;<br/>


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