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<div><span class="kw">theorem </span><a NAME="T13"><span class="comment"><font color="firebrick">:: CARD_4:13</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">D</font> being   non  <a href="xboole_0.html#V1" title="XBOOLE_0:attr.1">empty</a>   <a href="hidden.html#M2" title="HIDDEN:mode.2">set</a>   st <font color="Olive" title="b1">D</font> is  <a href="card_3.html#V4" title="CARD_3:attr.4">countable</a>  holds <br/><font color="Olive" title="b1">D</font> <a href="finseq_2.html#K3" title="FINSEQ_2:func.3">*</a>  is  <a href="card_3.html#V4" title="CARD_3:attr.4">countable</a> </div></div>
