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<div><span class="kw">theorem </span><a NAME="T9"><span class="comment"><font color="firebrick">:: PROB_1:9</font></span><br/></a><div class="add"> for <font color="Olive" title="b1">X</font> being    <a href="hidden.html#M2" title="HIDDEN:mode.2">set</a>  holds   <a href="setfam_1.html#K9" title="SETFAM_1:func.9">bool</a> <font color="Olive" title="b1">X</font> is   <a href="prob_1.html#NM1" title="PROB_1:NM.1">Field_Subset</a> of <font color="Olive" title="b1">X</font> ;<br/></div></div>
