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<b>let </b><font color="Maroon">XX</font> be  non <a href="struct_0.html#V3">empty</a> <a href="pre_topc.html#NM1">TopSpace</a>;<br/><b>let </b><font color="Maroon">X</font> be  non <a href="struct_0.html#V3">empty</a>  <a href="pre_topc.html#M1">SubSpace</a> of <font color="Maroon">XX</font>;<br/><b>let </b><font color="Maroon">D</font> be  non <a href="xboole_0.html#V1">empty</a>  <a href="eqrel_1.html#M1">a_partition</a> of the <a href="struct_0.html#U1">carrier</a> of <font color="Maroon">X</font>;<br/><b>let </b><font color="Maroon">W</font> be   <a href="pre_topc.html#NM2">Point</a> of <font color="Maroon">XX</font>;<br/>







<a NAME="E1:84"/><i><font color="Green">E24</font></i>: 
<font color="Maroon">D</font> <a href="tarski.html#R1">c=</a>  <a href="borsuk_1.html#K16" target="_self">TrivExt</a> <font color="Maroon">D</font>
 
<b>by </b><i><a class="ref" href="xboole_1.html#T7">XBOOLE_1:7</a></i>;<br/>
<b>assume </b><a NAME="E2:84"/><i><font color="Green">E29</font></i>: 
<font color="Maroon">W</font> <a href="hidden.html#R2">in</a> the <a href="struct_0.html#U1">carrier</a> of <font color="Maroon">X</font>
 ;<br/>

<b>then reconsider </b><font color="Maroon">p</font> = <font color="Maroon">W</font> as   <a href="pre_topc.html#NM2">Point</a> of <font color="Maroon">X</font> ;<br/>
<a NAME="E4:84"/>
<span class="p1">(<span class="default"><a href="borsuk_1.html#K2" target="_self">proj</a> <font color="Maroon">D</font></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">p</font> <a href="hidden.html#R2">in</a> <font color="Maroon">D</font>
 
;<br/>
<b>then reconsider </b><font color="Maroon">A</font> = <span class="p1">(<span class="default"><a href="borsuk_1.html#K15" target="_self">Proj</a> <font color="Maroon">D</font></span>)</span> <a href="funct_1.html#K1">.</a> <font color="Maroon">W</font> as    <a href="subset_1.html#M2">Element</a> of  <a href="borsuk_1.html#K16" target="_self">TrivExt</a> <font color="Maroon">D</font> <b>by </b><i/>;<br/>
<a NAME="E6:84"/>
<font color="Maroon">W</font> <a href="hidden.html#R2">in</a> <font color="Maroon">A</font>
 
<b>by </b><i>, </i>;<br/>
<b>hence </b><a NAME="E7:84"/>
<span class="p1">(<span class="default"><a href="borsuk_1.html#K15" target="_self">Proj</a> <span class="p2">(<span class="default"><a href="borsuk_1.html#K16" target="_self">TrivExt</a> <font color="Maroon">D</font></span>)</span></span>)</span> <a href="funct_2.html#K3">.</a> <font color="Maroon">W</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="borsuk_1.html#K15" target="_self">Proj</a> <font color="Maroon">D</font></span>)</span> <a href="funct_1.html#K1">.</a> <font color="Maroon">W</font>
 <b>by </b><i/>;<br/>


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