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<div><span class="kw">theorem </span><a NAME="T11"><span class="comment"><font color="firebrick">:: FINTOPO6:11</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">FT</font> being   non  <a href="struct_0.html#V2" title="STRUCT_0:attr.2">empty</a>   <a href="orders_2.html#L1" title="ORDERS_2:struct.1">RelStr</a> <br/>  for <font color="Olive" title="b2">P</font> being   <a href="struct_0.html#NM2" title="STRUCT_0:NM.2">Subset</a> of <font color="Olive" title="b1">FT</font> holds <br/> ( <font color="Olive" title="b2">P</font> is  <a href="fin_topo.html#V3" title="FIN_TOPO:attr.3">closed</a>  iff <font color="Olive" title="b2">P</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a>  is  <a href="fin_topo.html#V2" title="FIN_TOPO:attr.2">open</a>  )</div></div>
