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Re: [TF-ENT] RDFS entailment regime & inconsistencies

From: Chimezie Ogbuji <ogbujic@ccf.org>
Date: Thu, 01 Oct 2009 10:17:27 -0400
To: "Birte Glimm" <birte.glimm@comlab.ox.ac.uk>
cc: "SPARQL Working Group" <public-rdf-dawg@w3.org>
Message-ID: <C6EA3237.CC99%ogbujic@ccf.org>
Response / comments inline below (thanks for clarifications)

On 9/30/09 3:03 PM, "Birte Glimm" <birte.glimm@comlab.ox.ac.uk> wrote:
>> If we are talking about the latter inconsistency then doesn't this apply to
>> *any* entailment regime that is defined in terms of interpretations, models,
>> etc. (i.e., not just RDFS)?
> Well, for OWL (Lite, DL, EL, QL), for example, mal-formed lexical
> forms of literal cause a syntax error according to the spec.

Interpreting a malformed XML literal string as a syntax error that should
*not* effect the inference procedure for instance, seems intuitive to me
(even if it violates full RDFS semantics).

> In OWL QL,
> on the other hand and if I recall rightly, you cannot state
> inconsistencies, but you can have syntax errors (for literals) or
> axioms that are outside of what OWL QL is supposed to handle. This you
> do have to check when you parse the data, but it is a syntax check.

This is much more reasonable to implement.

> For OWL RL and RIF, I don't know from the top
> of my head, 

OWL2 RL includes a mechanism to identify inconsistencies as consequents in
entailments.  The rules regarding the "Semantics of Datatypes" are used in
the same way to identify 'syntax errors' as inconsistencies.

> There are several options (non absolutely ideal IMO), you could ( I am
> just mentioning some, I am not advocating any) declare mal-formed
> literals as syntax errors (against the RDFS spec).

+1

>> Well, if you are still guaranteed to terminate after the application of rule
>> lg, rule gl and the RDF and RDFS entailment rules (even in the face of an
>> XML clash), then you *will* stop, right?

> Yes, how does it happen that you stopped, but didn't find the clash?
> You can not apply all RDFS rules, you might know that some part of the
> graph is not relevant for the query so you don't look at that part,

This seems like very unintuitive behavior for querying against a set of
facts

-- Chime


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Received on Thursday, 1 October 2009 14:18:43 GMT

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