Re: on the turtle serialization of SHACL

On 12/14/2016 01:08 PM, David Booth wrote:
> 
> On 12/14/2016 03:29 PM, Simon Spero wrote:
>> It's valid (if redundant) RDF/XML, but it's invalid OWL;  there are
>> multiple instances of owl:Ontology in the file, which is forbidden in
>> the mapping document because there's no way to tell which axioms are
>> part of which ontology.
>>
>> There are even repeated declarations of the same ontology, at which
>> point even the non-strict parse mode OWLAPI gives up.  This causes
>> protégé and other related tools to reject the document  (the turtle
>> encoding parses OK).
> 
> If the protégé parser rejects the document because of duplicate triples then
> that is a bug in the parser, because it is not possible for an RDF graph to
> have duplicate triples:
> https://www.w3.org/TR/rdf11-concepts/#section-rdf-graph
> 
>   "An RDF graph is a set of RDF triples."
> 
> David Booth

The initial problem is that the document https://www.w3.org/ns/prov.owl (at
least as served as RDF/XML) contains multiple nodes that both have rdf:type
values of owl:Ontology and values for some ontology property.   This is not
allowed in RDF graphs that encode OWL 2 ontologies.

Tools that try to read OWL ontologies from documents that encode RDF graphs
may try lots of different things to recover from problems, including this one.
 For example, they might look at the document structure to try to assign
different parts of the document to different ontologies.

So it is not necessarily a bug in the tool that causes its heroic efforts to
fail.  It just may be that the tool is insufficiently intelligent to determine
how to determine how to extract one or more OWL 2 ontologies from the document
a document that does not meet the requirements for encoding an OWL 2 ontology.


It appears that this document includes multiple ontologies because it includes
imported files without first determining that this results in an OWL 2 ontology.


Peter F. Patel-Schneider
Nuance Communications

Received on Wednesday, 14 December 2016 22:04:38 UTC