esents (or, is identical
&gt; &gt; &gt; &gt; with) R (again, in the usual way)?  Ok.
&gt; &gt; &gt; &gt;
&gt; &gt; &gt; &gt; &gt; ---- note:  only binary relations are used.         &lt;&lt;&lt;---&lt;&lt;&lt;
&gt; 
&gt; What you mean is:  "only binary relations are mentioned."   &lt;&lt;&lt;---&lt;&lt;&lt;
&gt; 
&gt; &gt; &gt; &gt; It seems bizarre to me to limit oneself in principle to binary
&gt; &gt; &gt; &gt; relations.  Giving, for example, is a very natural 3-place relation.
&gt; &gt; &gt; &gt;
&gt; 