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<b>let </b><font color="Maroon" title="c1">T</font>, <font color="Maroon" title="c2">T1</font> be  non <a href="struct_0.html#V3" title="STRUCT_0:attr.3">empty</a> <a href="pre_topc.html#NM1" title="PRE_TOPC:NM.1">TopSpace</a>;<br/><b>let </b><font color="Maroon" title="c3">f</font> be  <a href="pre_topc.html#V5" title="PRE_TOPC:attr.5">continuous</a> <a href="struct_0.html#NM6" title="STRUCT_0:NM.6">Function</a> of <font color="Maroon" title="c1">T</font>,<font color="Maroon" title="c2">T1</font>;<br/>



<a NAME="E1:13"/><i><font color="Green" title="E7">A1</font></i>: 
(  <a href="relset_1.html#K4" title="RELSET_1:func.4">dom</a> <font color="Maroon" title="c3">f</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a> the <a href="struct_0.html#U1" title="STRUCT_0:sel.1">carrier</a> of <font color="Maroon" title="c1">T</font> &amp;  <a href="relset_1.html#K5" title="RELSET_1:func.5">rng</a> <font color="Maroon" title="c3">f</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a> the <a href="struct_0.html#U1" title="STRUCT_0:sel.1">carrier</a> of <font color="Maroon" title="c2">T1</font> )
 
<b>by </b><i><a class="ref" href="funct_2.html#D1" title="FUNCT_2:def.1">FUNCT_2:def 1</a></i>;<br/>
<b>assume </b><a NAME="E2:13"/><i><font color="Green" title="E8">A2</font></i>: 
<font color="Maroon" title="c2">T1</font> is <a href="urysohn1.html#V1" title="URYSOHN1:attr.1">being_T1</a>
 ;<br/>

<b>let </b><font color="Maroon" title="c4">w</font> be    <a href="hidden.html#M1" title="HIDDEN:mode.1">set</a> ;<br/><b>let </b><font color="Maroon" title="c5">x</font> be   <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c1">T</font>;<br/>



<b>assume </b><a NAME="E3:13"/><i><font color="Green" title="E9">A3</font></i>: 
<font color="Maroon" title="c4">w</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="eqrel_1.html#K12" title="EQREL_1:func.12">EqClass</a> <font color="Maroon" title="c5">x</font>,<span class="p1">(<span class="default"><a href="eqrel_1.html#K13" title="EQREL_1:func.13">Intersection</a> <span class="p2">(<span class="default"><a href="t_1topsp.html#K1" title="T_1TOPSP:func.1">Closed_Partitions</a> <font color="Maroon" title="c1">T</font></span>)</span></span>)</span>
 ;<br/>

<b>let </b><font color="Maroon" title="c6">y</font> be    <a href="hidden.html#M1" title="HIDDEN:mode.1">set</a> ; <i><font color="Red">:: according to </font></i><a class="ref" href="tarski.html#D3" title="TARSKI:def.3">TARSKI:def 3</a><br/>

<b>assume </b><a NAME="E4:13"/><i><font color="Green" title="E10">A4</font></i>: 
<font color="Maroon" title="c6">y</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c4">w</font>
 ;<br/>

<b>reconsider </b><font color="Maroon" title="c7">fz</font> = <span class="p1">{<span class="default"> <span class="p2">(<span class="default"><font color="Maroon" title="c3">f</font> <a href="relset_1.html#K11" title="RELSET_1:func.11">"</a> <span class="p3"><a href="domain_1.html#K6" title="DOMAIN_1:func.6">{</a><span class="default"><font color="Olive" title="b1">z</font></span><a href="domain_1.html#K6" title="DOMAIN_1:func.6">}</a></span></span>)</span> where <font color="Olive" title="b1">z</font> is   <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c2">T1</font> : <font color="Olive" title="b1">z</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="relset_1.html#K5" title="RELSET_1:func.5">rng</a> <font color="Maroon" title="c3">f</font> </span>}</span>  as    <a href="eqrel_1.html#M1" title="EQREL_1:mode.1">a_partition</a> of the <a href="struct_0.html#U1" title="STRUCT_0:sel.1">carrier</a> of <font color="Maroon" title="c1">T</font> <b>by </b><i><a class="txt" href="t_1topsp.html#E2:13"><i><font color="Green" title="E8">A2</font></i></a>, <a class="ref" href="t_1topsp.html#T13" target="_self" title="T_1TOPSP:th.13">Th13</a></i>;<br/>
<a NAME="E6:13"/>
for <font color="Olive" title="b1">A</font> being  <a href="struct_0.html#NM2" title="STRUCT_0:NM.2">Subset</a> of <font color="Maroon" title="c1">T</font>  st <font color="Olive" title="b1">A</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c7">fz</font> holds <br/><font color="Olive" title="b1">A</font> is <a href="pre_topc.html#V4" title="PRE_TOPC:attr.4">closed</a>
 
<b>by </b><i><a class="txt" href="t_1topsp.html#E2:13"><i><font color="Green" title="E8">A2</font></i></a>, <a class="ref" href="t_1topsp.html#T13" target="_self" title="T_1TOPSP:th.13">Th13</a></i>;<br/>
<a NAME="E7:13"/><b>then </b>
<font color="Maroon" title="c7">fz</font> is <a href="tops_2.html#V2" title="TOPS_2:attr.2">closed</a>
 
<b>by </b><i><a class="ref" href="tops_2.html#D2" title="TOPS_2:def.2">TOPS_2:def 2</a></i>;<br/>
<a NAME="E8:13"/><b>then </b>
<font color="Maroon" title="c7">fz</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1">{<span class="default"> <font color="Olive" title="b1">B</font> where <font color="Olive" title="b1">B</font> is    <a href="eqrel_1.html#M1" title="EQREL_1:mode.1">a_partition</a> of the <a href="struct_0.html#U1" title="STRUCT_0:sel.1">carrier</a> of <font color="Maroon" title="c1">T</font> : <font color="Olive" title="b1">B</font> is <a href="tops_2.html#V2" title="TOPS_2:attr.2">closed</a> </span>}</span> 
 
;<br/>
<a NAME="E9:13"/><b>then </b>
<font color="Maroon" title="c7">fz</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="t_1topsp.html#K1" title="T_1TOPSP:func.1">Closed_Partitions</a> <font color="Maroon" title="c1">T</font>
 
;<br/>
<a NAME="E10:13"/><b>then </b><i><font color="Green" title="E11">A5</font></i>: 
 <a href="eqrel_1.html#K12" title="EQREL_1:func.12">EqClass</a> <font color="Maroon" title="c5">x</font>,<font color="Maroon" title="c7">fz</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1">{<span class="default"> <span class="p2">(<span class="default"><a href="eqrel_1.html#K12" title="EQREL_1:func.12">EqClass</a> <font color="Maroon" title="c5">x</font>,<font color="Olive" title="b1">S</font></span>)</span> where <font color="Olive" title="b1">S</font> is    <a href="eqrel_1.html#M1" title="EQREL_1:mode.1">a_partition</a> of the <a href="struct_0.html#U1" title="STRUCT_0:sel.1">carrier</a> of <font color="Maroon" title="c1">T</font> : <font color="Olive" title="b1">S</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="t_1topsp.html#K1" title="T_1TOPSP:func.1">Closed_Partitions</a> <font color="Maroon" title="c1">T</font> </span>}</span> 
 
;<br/>
<a NAME="E11:13"/><i><font color="Green" title="E12">A6</font></i>: 
<font color="Maroon" title="c3">f</font> <a href="relset_1.html#K11" title="RELSET_1:func.11">"</a> <span class="p1"><a href="domain_1.html#K6" title="DOMAIN_1:func.6">{</a><span class="default"><span class="p2">(<span class="default"><font color="Maroon" title="c3">f</font> <a href="funct_2.html#K3" title="FUNCT_2:func.3">.</a> <font color="Maroon" title="c5">x</font></span>)</span></span><a href="domain_1.html#K6" title="DOMAIN_1:func.6">}</a></span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="eqrel_1.html#K12" title="EQREL_1:func.12">EqClass</a> <font color="Maroon" title="c5">x</font>,<font color="Maroon" title="c7">fz</font>
 
<div><a class="txt" onclick="hs2(this)" href="javascript:()" title="13_1"><b>proof </b></a><div class="add">

<a NAME="E1:13_1"/>
<font color="Maroon" title="c3">f</font> <a href="funct_2.html#K3" title="FUNCT_2:func.3">.</a> <font color="Maroon" title="c5">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <span class="p1"><a href="domain_1.html#K6" title="DOMAIN_1:func.6">{</a><span class="default"><span class="p2">(<span class="default"><font color="Maroon" title="c3">f</font> <a href="funct_2.html#K3" title="FUNCT_2:func.3">.</a> <font color="Maroon" title="c5">x</font></span>)</span></span><a href="domain_1.html#K6" title="DOMAIN_1:func.6">}</a></span>
 
<b>by </b><i><a class="ref" href="tarski.html#D1" title="TARSKI:def.1">TARSKI:def 1</a></i>;<br/>
<a NAME="E2:13_1"/><b>then </b><i><font color="Green" title="E13">A7</font></i>: 
<font color="Maroon" title="c5">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c3">f</font> <a href="relset_1.html#K11" title="RELSET_1:func.11">"</a> <span class="p1"><a href="domain_1.html#K6" title="DOMAIN_1:func.6">{</a><span class="default"><span class="p2">(<span class="default"><font color="Maroon" title="c3">f</font> <a href="funct_2.html#K3" title="FUNCT_2:func.3">.</a> <font color="Maroon" title="c5">x</font></span>)</span></span><a href="domain_1.html#K6" title="DOMAIN_1:func.6">}</a></span>
 
<b>by </b><i><a class="txt" href="t_1topsp.html#E1:13"><i><font color="Green" title="E7">A1</font></i></a>, <a class="ref" href="funct_1.html#D13" title="FUNCT_1:def.13">FUNCT_1:def 13</a></i>;<br/>
<a NAME="E3:13_1"/><i><font color="Green" title="E14">A8</font></i>: 
<font color="Maroon" title="c3">f</font> <a href="funct_2.html#K3" title="FUNCT_2:func.3">.</a> <font color="Maroon" title="c5">x</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="relset_1.html#K5" title="RELSET_1:func.5">rng</a> <font color="Maroon" title="c3">f</font>
 
<b>by </b><i><a class="txt" href="t_1topsp.html#E1:13"><i><font color="Green" title="E7">A1</font></i></a>, <a class="ref" href="funct_1.html#D5" title="FUNCT_1:def.5">FUNCT_1:def 5</a></i>;<br/>
<b>reconsider </b><font color="Maroon" title="c8">fx</font> = <font color="Maroon" title="c3">f</font> <a href="funct_2.html#K3" title="FUNCT_2:func.3">.</a> <font color="Maroon" title="c5">x</font> as   <a href="struct_0.html#NM1" title="STRUCT_0:NM.1">Element</a> of <font color="Maroon" title="c2">T1</font> ;<br/>
<a NAME="E5:13_1"/>
<font color="Maroon" title="c3">f</font> <a href="relset_1.html#K11" title="RELSET_1:func.11">"</a> <span class="p1"><a href="domain_1.html#K6" title="DOMAIN_1:func.6">{</a><span class="default"><font color="Maroon" title="c8">fx</font></span><a href="domain_1.html#K6" title="DOMAIN_1:func.6">}</a></span> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c7">fz</font>
 
<b>by </b><i><a class="txt" href="t_1topsp.html#E3:13_1"><i><font color="Green" title="E14">A8</font></i></a></i>;<br/>
<b>hence </b><a NAME="E6:13_1"/>
<font color="Maroon" title="c3">f</font> <a href="relset_1.html#K11" title="RELSET_1:func.11">"</a> <span class="p1"><a href="domain_1.html#K6" title="DOMAIN_1:func.6">{</a><span class="default"><span class="p2">(<span class="default"><font color="Maroon" title="c3">f</font> <a href="funct_2.html#K3" title="FUNCT_2:func.3">.</a> <font color="Maroon" title="c5">x</font></span>)</span></span><a href="domain_1.html#K6" title="DOMAIN_1:func.6">}</a></span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="eqrel_1.html#K12" title="EQREL_1:func.12">EqClass</a> <font color="Maroon" title="c5">x</font>,<font color="Maroon" title="c7">fz</font>
 <b>by </b><i><a class="txt" href="t_1topsp.html#E2:13_1"><i><font color="Green" title="E13">A7</font></i></a>, <a class="ref" href="eqrel_1.html#D8" title="EQREL_1:def.8">EQREL_1:def 8</a></i>;<br/>


</div><b>end;</b></div>
<a NAME="E12:13"/>
 <a href="eqrel_1.html#K12" title="EQREL_1:func.12">EqClass</a> <font color="Maroon" title="c5">x</font>,<span class="p1">(<span class="default"><a href="eqrel_1.html#K13" title="EQREL_1:func.13">Intersection</a> <span class="p2">(<span class="default"><a href="t_1topsp.html#K1" title="T_1TOPSP:func.1">Closed_Partitions</a> <font color="Maroon" title="c1">T</font></span>)</span></span>)</span> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="setfam_1.html#K1" title="SETFAM_1:func.1">meet</a> <span class="p1">{<span class="default"> <span class="p2">(<span class="default"><a href="eqrel_1.html#K12" title="EQREL_1:func.12">EqClass</a> <font color="Maroon" title="c5">x</font>,<font color="Olive" title="b1">S</font></span>)</span> where <font color="Olive" title="b1">S</font> is    <a href="eqrel_1.html#M1" title="EQREL_1:mode.1">a_partition</a> of the <a href="struct_0.html#U1" title="STRUCT_0:sel.1">carrier</a> of <font color="Maroon" title="c1">T</font> : <font color="Olive" title="b1">S</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="t_1topsp.html#K1" title="T_1TOPSP:func.1">Closed_Partitions</a> <font color="Maroon" title="c1">T</font> </span>}</span> 
 
<b>by </b><i><a class="ref" href="eqrel_1.html#D11" title="EQREL_1:def.11">EQREL_1:def 11</a></i>;<br/>
<b>hence </b><a NAME="E13:13"/>
<font color="Maroon" title="c6">y</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a> <font color="Maroon" title="c3">f</font> <a href="relset_1.html#K11" title="RELSET_1:func.11">"</a> <span class="p1"><a href="domain_1.html#K6" title="DOMAIN_1:func.6">{</a><span class="default"><span class="p2">(<span class="default"><font color="Maroon" title="c3">f</font> <a href="funct_2.html#K3" title="FUNCT_2:func.3">.</a> <font color="Maroon" title="c5">x</font></span>)</span></span><a href="domain_1.html#K6" title="DOMAIN_1:func.6">}</a></span>
 <b>by </b><i><a class="txt" href="t_1topsp.html#E3:13"><i><font color="Green" title="E9">A3</font></i></a>, <a class="txt" href="t_1topsp.html#E4:13"><i><font color="Green" title="E10">A4</font></i></a>, <a class="txt" href="t_1topsp.html#E10:13"><i><font color="Green" title="E11">A5</font></i></a>, <a class="txt" href="t_1topsp.html#E11:13"><i><font color="Green" title="E12">A6</font></i></a>, <a class="ref" href="setfam_1.html#D1" title="SETFAM_1:def.1">SETFAM_1:def 1</a></i>;<br/>


</div>
