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<b>let </b><font color="Maroon" title="c1">Y</font> be  non <a href="struct_0.html#V2" title="STRUCT_0:attr.2">empty</a>  <a href="pre_topc.html#L1" title="PRE_TOPC:struct.1">TopStruct</a> ;<br/><b>let </b><font color="Maroon" title="c2">y</font> be   <a href="pre_topc.html#NM2" title="PRE_TOPC:NM.2">Point</a> of <font color="Maroon" title="c1">Y</font>;<br/>



<b>assume </b><a NAME="E1:44"/><i><font color="Green" title="E15">A1</font></i>: 
 <a href="tex_2.html#K1" title="TEX_2:func.1">Sspace</a> <font color="Maroon" title="c2">y</font> is <a href="tex_2.html#V2" title="TEX_2:attr.2">proper</a>
 ;<br/>

<b>assume </b><a NAME="E2:44"/>
<font color="Maroon" title="c1">Y</font> is <a href="struct_0.html#V7" title="STRUCT_0:attr.7">trivial</a>
 ;<br/>

<b>then reconsider </b><font color="Maroon" title="c3">Y</font> = <font color="Maroon" title="c1">Y</font> as  non <a href="struct_0.html#V2" title="STRUCT_0:attr.2">empty</a> <a href="struct_0.html#V7" title="STRUCT_0:attr.7">trivial</a>  <a href="pre_topc.html#L1" title="PRE_TOPC:struct.1">TopStruct</a>  ;<br/>
<a NAME="E4:44"/>
 <a href="tex_2.html#K1" title="TEX_2:func.1">Sspace</a> <font color="Maroon" title="c2">y</font> is  non <a href="struct_0.html#V2" title="STRUCT_0:attr.2">empty</a>  <a href="pre_topc.html#M1" title="PRE_TOPC:mode.1">SubSpace</a> of <font color="Maroon" title="c3">Y</font>
 
;<br/>
<b>hence </b><a NAME="E5:44"/>
contradiction
 <b>by </b><i><a class="txt" href="tex_2.html#E1:44"><i><font color="Green" title="E15">A1</font></i></a></i>;<br/>


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