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<div><span class="kw">theorem </span><span class="lab"><font color="Green" title="E36">Th42</font></span>: <a NAME="T42"><span class="comment"><font color="firebrick">:: TOPGEN_5:42</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">A</font> being   <a href="subset_1.html#NM2" title="SUBSET_1:NM.2">Subset</a> of <a href="topgen_5.html#K1" title="TOPGEN_5:func.1">y=0-line</a> holds  <font color="Olive" title="b1">A</font> is   <a href="pre_topc.html#V4" title="PRE_TOPC:attr.4">closed</a>  <a href="struct_0.html#NM2" title="STRUCT_0:NM.2">Subset</a> of <a href="topgen_5.html#K3" title="TOPGEN_5:func.3">Niemytzki-plane</a></div></div>
