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<div><span class="kw">theorem </span><span class="lab"><font color="Green" title="E11">Th21</font></span>: <a NAME="T19"><span class="comment"><font color="firebrick">:: LOPBAN15:19</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">X</font>, <font color="Olive" title="b2">Y</font> being   <a href="rlvect_1.html#NM2" title="RLVECT_1:NM.2">RealLinearSpace</a><br/>  for <font color="Olive" title="b3">X1</font> being    <a href="rlsub_1.html#M1" title="RLSUB_1:mode.1">Subspace</a> of <font color="Olive" title="b1">X</font><br/>  for <font color="Olive" title="b4">Y1</font> being    <a href="rlsub_1.html#M1" title="RLSUB_1:mode.1">Subspace</a> of <font color="Olive" title="b2">Y</font> holds  <span class="p1"><a href="prvect_3.html#K6" title="PRVECT_3:func.6">[:</a><span class="default"><font color="Olive" title="b3">X1</font>,<font color="Olive" title="b4">Y1</font></span><a href="prvect_3.html#K6" title="PRVECT_3:func.6">:]</a></span> is    <a href="rlsub_1.html#M1" title="RLSUB_1:mode.1">Subspace</a> of <span class="p1"><a href="prvect_3.html#K6" title="PRVECT_3:func.6">[:</a><span class="default"><font color="Olive" title="b1">X</font>,<font color="Olive" title="b2">Y</font></span><a href="prvect_3.html#K6" title="PRVECT_3:func.6">:]</a></span></div></div>
