Declarative limitations of OWL/DAML

Hi,

I'm interested in what CANNOT be represented (declared) in OWL/DAML. Your 
comments or pointers to papers are much appreciated.

What I'm hoping to do is to be able to represent constraints (or axioms or 
rules) in a DAML ontology so that an inferencing engine can check the ontology 
for consistency.  For instance, if I have

<age rdf:about="#Tom"> <age_type rdf:about="#child"/> </age>
<age rdf:about="#John> <age_type rdf:about="#man"/> </age>
<less rdf:about="#child"> <age_type rdf:about="#man"/> </less>

in the DAML ontology, I would like to define an axiom <younger> in terms of 
<age> and <less> in such a way that the additional statement

<younger rdf:about="#John"> <age_type rdf:about="#Tom"/> </younger>

would be flagged as inconsistent.

Much thanks