by Church and Kleene in
&gt; &gt; the 30s) is an approach to computability theory (though, notably,
&gt; &gt; has also been used more recently in the semantics of natural
&gt; &gt; language as the basis of a theory of properties and relations).  The
&gt; &gt; untyped calculus, while powerful and flexible, is also
&gt; &gt; mathematically very complex, and I haven't seen anything in ontology
&gt; &gt; that requires it.  Perhaps if you said what a "constraint" is.  Are
&gt; &gt; you simply talking about the a