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<div><span class="kw">theorem </span><span class="lab"><font color="Green" title="E32">Th48</font></span>: <a NAME="T48"><span class="comment"><font color="firebrick">:: TOPS_1:48</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">GX</font> being    <a href="pre_topc.html#L1" title="PRE_TOPC:struct.1">TopStruct</a> <br/>  for <font color="Olive" title="b2">R</font> being   <a href="struct_0.html#NM2" title="STRUCT_0:NM.2">Subset</a> of <font color="Olive" title="b1">GX</font> holds <br/> ( <font color="Olive" title="b2">R</font> is  <a href="tops_1.html#V2" title="TOPS_1:attr.2">boundary</a>  iff  <a href="tops_1.html#K1" title="TOPS_1:func.1">Int</a> <font color="Olive" title="b2">R</font> <a href="hidden.html#R1" title="HIDDEN:pred.1">=</a>  <a href="xboole_0.html#K1" title="XBOOLE_0:func.1">{}</a>  )</div></div>
