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<div><span class="kw">theorem </span><a NAME="T52"><span class="comment"><font color="firebrick">:: TOPS_1:52</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 <font color="Olive" title="b2">R</font> <a href="tarski.html#R1" title="TARSKI:pred.1">c=</a>  <a href="tops_1.html#K2" title="TOPS_1:func.2">Fr</a> <font color="Olive" title="b2">R</font> )</div></div>
