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<b>let </b><font color="Maroon">T1</font> be   <a href="pre_topc.html#NM1">TopSpace</a>, <font color="Maroon">T2</font> be   <a href="pre_topc.html#NM1">TopSpace</a>;<br/>

<b>assume </b><a NAME="E1:38"/>
( <font color="Maroon">T1</font> is <a href="compts_1.html#V2">compact</a> &amp; <font color="Maroon">T2</font> is <a href="compts_1.html#V2">compact</a> )
 ;<br/>

<b>then reconsider </b><font color="Maroon">T1</font> = <font color="Maroon">T1</font>, <font color="Maroon">T2</font> = <font color="Maroon">T2</font> as  <a href="compts_1.html#V2">compact</a> <a href="pre_topc.html#NM1">TopSpace</a> ;<br/>
<div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="38_1"><b>per </b></a><a class="txt" onclick="hs(this)" href="javascript:()"><b>cases </b></a><span class="hide"><a NAME="E1:38_1"/>
( ( not <font color="Maroon">T1</font> is <a href="struct_0.html#V3">empty</a> &amp; not <font color="Maroon">T2</font> is <a href="struct_0.html#V3">empty</a> ) or ( <font color="Maroon">T1</font> is <a href="struct_0.html#V3">empty</a> &amp; <font color="Maroon">T2</font> is <a href="struct_0.html#V3">empty</a> ) or ( <font color="Maroon">T1</font> is <a href="struct_0.html#V3">empty</a> &amp; not <font color="Maroon">T2</font> is <a href="struct_0.html#V3">empty</a> ) or ( not <font color="Maroon">T1</font> is <a href="struct_0.html#V3">empty</a> &amp; <font color="Maroon">T2</font> is <a href="struct_0.html#V3">empty</a> ) )
 </span>;<br/><div class="add"><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="38_1_1"><b>suppose </b></a><a NAME="E1:38_1_1"/>
( not <font color="Maroon">T1</font> is <a href="struct_0.html#V3">empty</a> &amp; not <font color="Maroon">T2</font> is <a href="struct_0.html#V3">empty</a> )
 ;<br/><div class="add"><b>hence </b><a NAME="E2:38_1_1"/>
<span class="p1"><a href="borsuk_1.html#K5">[:</a><span class="default"><font color="Maroon">T1</font>,<font color="Maroon">T2</font></span><a href="borsuk_1.html#K5">:]</a></span> is <a href="compts_1.html#V2">compact</a>
 <b>by </b><i/>;<br/></div><b>end;</b></div><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="38_1_2"><b>suppose </b></a><a NAME="E1:38_1_2"/>
( <font color="Maroon">T1</font> is <a href="struct_0.html#V3">empty</a> &amp; <font color="Maroon">T2</font> is <a href="struct_0.html#V3">empty</a> )
 ;<br/><div class="add"><a NAME="E2:38_1_2"/><b>then </b>
<span class="p1"><a href="borsuk_1.html#K5">[:</a><span class="default"><font color="Maroon">T1</font>,<font color="Maroon">T2</font></span><a href="borsuk_1.html#K5">:]</a></span> is <a href="struct_0.html#V3">empty</a>
 <b>by </b><i/>;<br/><b>hence </b><a NAME="E3:38_1_2"/>
<span class="p1"><a href="borsuk_1.html#K5">[:</a><span class="default"><font color="Maroon">T1</font>,<font color="Maroon">T2</font></span><a href="borsuk_1.html#K5">:]</a></span> is <a href="compts_1.html#V2">compact</a>
 <b>by </b><i/>;<br/></div><b>end;</b></div><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="38_1_3"><b>suppose </b></a><a NAME="E1:38_1_3"/>
( <font color="Maroon">T1</font> is <a href="struct_0.html#V3">empty</a> &amp; not <font color="Maroon">T2</font> is <a href="struct_0.html#V3">empty</a> )
 ;<br/><div class="add"><a NAME="E2:38_1_3"/><b>then </b>
<span class="p1"><a href="borsuk_1.html#K5">[:</a><span class="default"><font color="Maroon">T1</font>,<font color="Maroon">T2</font></span><a href="borsuk_1.html#K5">:]</a></span> is <a href="struct_0.html#V3">empty</a>
 <b>by </b><i/>;<br/><b>hence </b><a NAME="E3:38_1_3"/>
<span class="p1"><a href="borsuk_1.html#K5">[:</a><span class="default"><font color="Maroon">T1</font>,<font color="Maroon">T2</font></span><a href="borsuk_1.html#K5">:]</a></span> is <a href="compts_1.html#V2">compact</a>
 <b>by </b><i/>;<br/></div><b>end;</b></div><div><a class="txt" onclick="hsNdiv(this)" href="javascript:()" title="38_1_4"><b>suppose </b></a><a NAME="E1:38_1_4"/>
( not <font color="Maroon">T1</font> is <a href="struct_0.html#V3">empty</a> &amp; <font color="Maroon">T2</font> is <a href="struct_0.html#V3">empty</a> )
 ;<br/><div class="add"><a NAME="E2:38_1_4"/><b>then </b>
<span class="p1"><a href="borsuk_1.html#K5">[:</a><span class="default"><font color="Maroon">T1</font>,<font color="Maroon">T2</font></span><a href="borsuk_1.html#K5">:]</a></span> is <a href="struct_0.html#V3">empty</a>
 <b>by </b><i/>;<br/><b>hence </b><a NAME="E3:38_1_4"/>
<span class="p1"><a href="borsuk_1.html#K5">[:</a><span class="default"><font color="Maroon">T1</font>,<font color="Maroon">T2</font></span><a href="borsuk_1.html#K5">:]</a></span> is <a href="compts_1.html#V2">compact</a>
 <b>by </b><i/>;<br/></div><b>end;</b></div></div><b>end;</b></div>

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