their elements are objects
    of signs of a sort that we call &quot;mathematical&quot;.  In most settings,
    the descriptors &quot;formal&quot; or &quot;logical&quot; will convey the point just
    as well as &quot;mathematical&quot;.  These adjectives are meant to impart
    no more than the fact that the meanings of the signs in question
    are determined solely by bodies of formal, logical, mathematical
    expressions that we know as &quot;theories&quot;.
 
JA: 3.  Mathematical objects are not physi