 &gt; &gt;the set itself is present?  These are the sorts of questions anyone
&gt; &gt; &gt;might have when reading this definition.
&gt; &gt; &gt;
&gt; &gt; &gt;My recommendation is that we should focus on getting rich
&gt; &gt; &gt;definitions written for these concepts, so that we can all
&gt; &gt; &gt;understand them before we go any further.  The definitions should
&gt; &gt; &gt;include all the explanatory text we can create, including
&gt; &gt; &gt;discussions of where the boundaries of each concept a