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<b>let </b><font color="Maroon">Y</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">X</font> be    <a href="hidden.html#M1">set</a> ;<br/><b>let </b><font color="Maroon">Z</font> be    <a href="hidden.html#M1">set</a> ;<br/>





<a NAME="E1:9"/>
 <a href="classes1.html#K1" target="_self">Tarski-Class</a> <font color="Maroon">X</font> <a href="classes1.html#R1" target="_self">is_Tarski-Class_of</a> <font color="Maroon">X</font>
 
<b>by </b><i/>;<br/>
<a NAME="E2:9"/><b>then </b>
 <a href="classes1.html#K1" target="_self">Tarski-Class</a> <font color="Maroon">X</font> <a href="classes1.html#NR1" target="_self">is_Tarski-Class</a> 
 
<b>by </b><i/>;<br/>
<a NAME="E3:9"/><b>then </b>
 <a href="classes1.html#K1" target="_self">Tarski-Class</a> <font color="Maroon">X</font> is <a href="classes1.html#V1" target="_self">subset-closed</a>
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E4:9"/>
( <font color="Maroon">Y</font> <a href="hidden.html#R2">in</a>  <a href="classes1.html#K1" target="_self">Tarski-Class</a> <font color="Maroon">X</font> &amp; <font color="Maroon">Z</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">Y</font> implies <font color="Maroon">Z</font> <a href="hidden.html#R2">in</a>  <a href="classes1.html#K1" target="_self">Tarski-Class</a> <font color="Maroon">X</font> )
 <b>by </b><i/>;<br/>


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