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<div><span class="kw">theorem </span><a NAME="T9"><span class="comment"><font color="firebrick">:: DUALSP04:9</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">X</font> being   <a href="bhsp_1.html#NM1" title="BHSP_1:NM.1">RealUnitarySpace</a><br/>  for <font color="Olive" title="b2">Y</font> being   <a href="struct_0.html#NM2" title="STRUCT_0:NM.2">Subset</a> of <font color="Olive" title="b1">X</font> holds <br/> ( <font color="Olive" title="b2">Y</font> is  <a href="dualsp04.html#V1" title="DUALSP04:attr.1">open</a>  iff <font color="Olive" title="b2">Y</font> <a href="subset_1.html#K3" title="SUBSET_1:func.3">`</a>  is  <a href="dualsp04.html#V2" title="DUALSP04:attr.2">closed</a>  )</div></div>
