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<span class="kw">let </span><font color="Maroon" title="c2">A</font> be   <a href="struct_0.html#NM2" title="STRUCT_0:NM.2">Subset</a> of <font color="Maroon" title="c1">T</font>; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="Red">::  thesis: </font></span></a><span class="hide"> ( <font color="Maroon" title="c2">A</font> is  <a href="topgen_4.html#V6" title="TOPGEN_4:attr.6">G_delta</a>  implies <font color="Maroon" title="c2">A</font> is  <a href="topgen_4.html#V8" title="TOPGEN_4:attr.8">Borel</a>  )</span><br/>

<span class="kw">assume </span><a NAME="E1:112_1_1"/>
<font color="Maroon" title="c2">A</font> is  <a href="topgen_4.html#V6" title="TOPGEN_4:attr.6">G_delta</a> 
 ; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="Red">::  thesis: </font></span></a><span class="hide"> <font color="Maroon" title="c2">A</font> is  <a href="topgen_4.html#V8" title="TOPGEN_4:attr.8">Borel</a> </span><br/>

<span class="kw">then </span><span class="kw">consider </span><font color="Maroon" title="c3">F</font> being   <a href="card_3.html#V4" title="CARD_3:attr.4">countable</a>   <a href="tops_2.html#V1" title="TOPS_2:attr.1">open</a>  <a href="struct_0.html#NM3" title="STRUCT_0:NM.3">Subset-Family</a> of <font color="Maroon" title="c1">T</font><span class="kw"> such that </span><br/><a NAME="E3:112_1_1"/><span class="lab"><font color="Green" title="E55">A1</font></span>: 
<font color="Maroon" title="c2">A</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="setfam_1.html#K6" title="SETFAM_1:func.6">meet</a> <font color="Maroon" title="c3">F</font>
 <span class="kw">by</span> <span class="lab"><a class="ref" href="topgen_4.html#D7" target="_self" title="TOPGEN_4:def.7">Def7</a></span>;<br/>
<a NAME="E4:112_1_1"/>
<font color="Maroon" title="c3">F</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a>  <a href="topgen_4.html#K5" title="TOPGEN_4:func.5">BorelSets</a> <font color="Maroon" title="c1">T</font>
 
<span class="kw">by</span> <span class="lab"><a class="ref" href="topgen_4.html#T69" target="_self" title="TOPGEN_4:th.69">Th69</a></span>;<br/>
<a NAME="E5:112_1_1"/><span class="kw">then </span>
<font color="Maroon" title="c2">A</font> <a href="hidden.html#R2" title="HIDDEN:pred.2">in</a>  <a href="topgen_4.html#K5" title="TOPGEN_4:func.5">BorelSets</a> <font color="Maroon" title="c1">T</font>
 
<span class="kw">by</span> <span class="lab"><a class="txt" href="#E3:112_1_1"><span class="lab"><font color="Green" title="E55">A1</font></span></a>, <a class="ref" href="topgen_4.html#D5" target="_self" title="TOPGEN_4:def.5">Def5</a></span>;<br/>
<span class="kw">hence </span><a NAME="E6:112_1_1"/>
<font color="Maroon" title="c2">A</font> is  <a href="topgen_4.html#V8" title="TOPGEN_4:attr.8">Borel</a> 
 <span class="kw">by</span> <span class="lab"><a class="ref" href="topgen_4.html#D12" target="_self" title="TOPGEN_4:def.12">Def12</a></span>; <a class="txt" onclick="hs(this)" href="javascript:()"><span class="comment"><font color="Red">::  thesis: </font></span></a><span class="hide"> verum</span><br/>


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