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<b>let </b><font color="Maroon">M</font> be  non <a href="struct_0.html#V3">empty</a> <a href="metric_1.html#NM1">MetrSpace</a>;<br/><b>let </b><font color="Maroon">A</font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">M</font>;<br/><b>let </b><font color="Maroon">B</font> be  non <a href="xboole_0.html#V1">empty</a> <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">M</font>;<br/><b>let </b><font color="Maroon">C</font> be   <a href="struct_0.html#NM2">Subset</a> of <span class="p1">(<span class="default"><font color="Maroon">M</font> <a href="topmetr.html#K1">|</a> <font color="Maroon">B</font></span>)</span>;<br/>







<b>assume </b><a NAME="E1:18"/><i><font color="Green">E26</font></i>: 
( <font color="Maroon">A</font> <a href="tarski.html#R1">c=</a> <font color="Maroon">B</font> &amp; <font color="Maroon">A</font> <a href="hidden.html#R1">=</a> <font color="Maroon">C</font> &amp; <font color="Maroon">C</font> is <a href="tbsp_1.html#V6">bounded</a> )
 ;<br/>

<b>then consider </b><font color="Maroon">r0</font> being   <a href="real_1.html#NM1">Real</a><b> such that </b><br/><a NAME="E3:18"/><i><font color="Green">E27</font></i>: 
( 0 <a href="xxreal_0.html#R1">&lt;</a> <font color="Maroon">r0</font> &amp; ( for <font color="Olive">x</font>, <font color="Olive">y</font> being  <a href="pre_topc.html#NM2">Point</a> of <span class="p1">(<span class="default"><font color="Maroon">M</font> <a href="topmetr.html#K1">|</a> <font color="Maroon">B</font></span>)</span>  st <font color="Olive">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">C</font> &amp; <font color="Olive">y</font> <a href="hidden.html#R2">in</a> <font color="Maroon">C</font> holds <br/> <a href="metric_1.html#K4">dist</a> <font color="Olive">x</font>,<font color="Olive">y</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">r0</font> ) )
 <b>by </b><i><a class="ref" href="tbsp_1.html#D9">TBSP_1:def 9</a></i>;<br/>
<a NAME="E4:18"/>
for <font color="Olive">x</font>, <font color="Olive">y</font> being  <a href="pre_topc.html#NM2">Point</a> of <font color="Maroon">M</font>  st <font color="Olive">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">A</font> &amp; <font color="Olive">y</font> <a href="hidden.html#R2">in</a> <font color="Maroon">A</font> holds <br/> <a href="metric_1.html#K4">dist</a> <font color="Olive">x</font>,<font color="Olive">y</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">r0</font>
 
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="18_1"><b>proof </b></a><div class="add">

<b>let </b><font color="Maroon">x</font> be   <a href="pre_topc.html#NM2">Point</a> of <font color="Maroon">M</font>, <font color="Maroon">y</font> be   <a href="pre_topc.html#NM2">Point</a> of <font color="Maroon">M</font>;<br/>

<b>assume </b><a NAME="E1:18_1"/><i><font color="Green">E36</font></i>: 
( <font color="Maroon">x</font> <a href="hidden.html#R2">in</a> <font color="Maroon">A</font> &amp; <font color="Maroon">y</font> <a href="hidden.html#R2">in</a> <font color="Maroon">A</font> )
 ;<br/>

<b>then reconsider </b><font color="Maroon">x0</font> = <font color="Maroon">x</font>, <font color="Maroon">y0</font> = <font color="Maroon">y</font> as   <a href="pre_topc.html#NM2">Point</a> of <span class="p1">(<span class="default"><font color="Maroon">M</font> <a href="topmetr.html#K1">|</a> <font color="Maroon">B</font></span>)</span> <b>by </b><i/>;<br/>
<a NAME="E3:18_1"/><i><font color="Green">E39</font></i>: 
 <a href="metric_1.html#K4">dist</a> <font color="Maroon">x0</font>,<font color="Maroon">y0</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">r0</font>
 
<b>by </b><i>, , </i>;<br/>
<a NAME="E4:18_1"/><i><font color="Green">E45</font></i>: 
the <a href="metric_1.html#U1">distance</a> of <span class="p1">(<span class="default"><font color="Maroon">M</font> <a href="topmetr.html#K1">|</a> <font color="Maroon">B</font></span>)</span> <a href="metric_1.html#K1">.</a> <font color="Maroon">x0</font>,<font color="Maroon">y0</font> <a href="hidden.html#R1">=</a> the <a href="metric_1.html#U1">distance</a> of <font color="Maroon">M</font> <a href="metric_1.html#K1">.</a> <font color="Maroon">x</font>,<font color="Maroon">y</font>
 
<b>by </b><i><a class="ref" href="topmetr.html#D1">TOPMETR:def 1</a></i>;<br/>
<a NAME="E5:18_1"/>
the <a href="metric_1.html#U1">distance</a> of <span class="p1">(<span class="default"><font color="Maroon">M</font> <a href="topmetr.html#K1">|</a> <font color="Maroon">B</font></span>)</span> <a href="metric_1.html#K1">.</a> <font color="Maroon">x0</font>,<font color="Maroon">y0</font> <a href="hidden.html#R1">=</a>  <a href="metric_1.html#K4">dist</a> <font color="Maroon">x0</font>,<font color="Maroon">y0</font>
 
<b>by </b><i><a class="ref" href="metric_1.html#D1">METRIC_1:def 1</a></i>;<br/>
<b>hence </b><a NAME="E6:18_1"/>
 <a href="metric_1.html#K4">dist</a> <font color="Maroon">x</font>,<font color="Maroon">y</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">r0</font>
 <b>by </b><i>, <a class="ref" href="hausdorf.html#T1" target="_self">Th1</a>, <a class="ref" href="metric_1.html#D1">METRIC_1:def 1</a></i>;<br/>


</div><b>end;</b></div>
<b>hence </b><a NAME="E5:18"/>
<font color="Maroon">A</font> is <a href="tbsp_1.html#V6">bounded</a>
 <b>by </b><i>, <a class="ref" href="tbsp_1.html#D9">TBSP_1:def 9</a></i>;<br/>


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