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<b>let </b><font color="Maroon">n</font> be    <a href="subset_1.html#M1">Element</a> of  <a href="numbers.html#K5">NAT</a> ;<br/><b>let </b><font color="Maroon">r</font> be   <a href="real_1.html#NM1">Real</a>;<br/><b>let </b><font color="Maroon">z</font> be    <a href="finseq_2.html#M2">Element</a> of  <a href="complsp1.html#K8" target="_self">COMPLEX</a> <font color="Maroon">n</font>;<br/><b>let </b><font color="Maroon">A</font> be   <a href="subset_1.html#NM2">Subset</a> of <span class="p1">(<span class="default"><a href="complsp1.html#K8" target="_self">COMPLEX</a> <font color="Maroon">n</font></span>)</span>;<br/>







<a NAME="E1:92"/>
( <font color="Maroon">z</font> <a href="hidden.html#R2">in</a> <span class="p1">{<span class="default"> <font color="Olive">z2</font> where <font color="Olive">z2</font> is    <a href="finseq_2.html#M2">Element</a> of  <a href="complsp1.html#K8" target="_self">COMPLEX</a> <font color="Maroon">n</font> :  <a href="complsp1.html#K18" target="_self">dist</a> <font color="Olive">z2</font>,<font color="Maroon">A</font> <a href="xxreal_0.html#R1">&lt;</a> <font color="Maroon">r</font> </span>}</span>  iff  ex <font color="Olive">z1</font> being   <a href="finseq_2.html#M2">Element</a> of  <a href="complsp1.html#K8" target="_self">COMPLEX</a> <font color="Maroon">n</font> st <br/>( <font color="Maroon">z</font> <a href="hidden.html#R1">=</a> <font color="Olive">z1</font> &amp;  <a href="complsp1.html#K18" target="_self">dist</a> <font color="Olive">z1</font>,<font color="Maroon">A</font> <a href="xxreal_0.html#R1">&lt;</a> <font color="Maroon">r</font> ) )
 
;<br/>
<b>hence </b><a NAME="E2:92"/>
( <font color="Maroon">z</font> <a href="hidden.html#R2">in</a>  <a href="complsp1.html#K19" target="_self">Ball</a> <font color="Maroon">A</font>,<font color="Maroon">r</font> iff  <a href="complsp1.html#K18" target="_self">dist</a> <font color="Maroon">z</font>,<font color="Maroon">A</font> <a href="xxreal_0.html#R1">&lt;</a> <font color="Maroon">r</font> )
 ;<br/>


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