Small problem with Expression.owl

Now that SWRL-Conditions aren't literals anymore, the following, in the
1.2 Expression.owl, makes that file
OWL Full (since we are "redefining rdf:nil"):

<SWRL-Condition rdf:ID="AlwaysTrue">
  <rdfs:label>Always True</rdfs:label>
  <rdfs:comment>
    An empty AtomList always evaluates to true. Note that this is not
equivalent to specifiying no
    precondition. Due to open-world semantics of OWL, it would not be
possible to distinguish
    having no precondition from not knowing the precondition. We would
need to specify a
    cardinality 0 restriction on precondition property to indicate that
there is no precondition
    which would be also valid.
  </rdfs:comment>
  <expressionLanguage rdf:resource="&expr;#SWRL"/>
  <expressionObject>
    <swrl:AtomList rdf:about="&rdf;#nil"/>
  </expressionObject>
</SWRL-Condition>

An easy solution would be to move the AlwaysTrue instance to a separate
file, which would only be imported by OWL-S services that use SWRL. That
way other services could still stay in OWL DL. Perhaps a little ugly to
have a file with just one instance though.

Daniel

Received on Thursday, 23 June 2005 03:21:22 UTC