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Typing and declarations -- a summary

From: Boris Motik <boris.motik@comlab.ox.ac.uk>
Date: Sat, 15 Dec 2007 20:17:17 -0000
To: "'Web Ontology Language \(\(OWL\)\) Working Group WG'" <public-owl-wg@w3.org>
Message-ID: <000e01c83f57$7d4b9870$2711a8c0@wolf>


My previous two e-mails were quite long, and they touch on problems that are somehow connected, but in a quite an intricate way.
Therefore, I wanted to summarize possible solutions and their pros and cons in a separate e-mail. This gives us the opportunity to
vote for a solution at the telco. I included the combinations that I deem realistic.

Q1. T2 for typing, D1 for declarations

Summary: We put typing triples in each document whether an entity is used,
         and we use owl11:declaredAs for declarations.


1. Ease of implementation: Each ontology can be parsed separately, which, I believe, will dramatically reduce the number of bugs.

2. Better performance: No need to go through the whole import closure twice.


1. More complex vocabulary.

2. Propagation of information as described by Alan Ruttenberg. Not everybody agrees that this is really an issue.

Aside: this is the current solution in OWL 1.1

Q2. T3 for typing, D2 for declarations

Summary: We require declarations for each entity used in any ontology, which are encoded
         using rdf:type. Typing triples are not replicated across the imports, but are
         placed only in the ontology where an entity is used.


1. Simpler vocabulary: I can see the intuitive appeal of this solution.

2. No propagation of information. Not everybody agrees that this is really an issue.


1. Problems for implementations: As I already described, hunting for triples across imported ontologies is really difficult. Feel
the wrath of the developers' community :-)

2. Performance problems: It might be necessary to go through the import closure twice.

3. Fragility: Assume that O imports O' and reuses some of the vocabulary of O'. Assume also that the user makes O not import O'.
Oops, the ontology O suddenly changed into a non-OWL-DL ontology. Hence, users might not be able to even load O into Protégé to fix
the problem.

Q3. Orthogonal issue: Allow T1 for punning

Regardless of our choices for Q1 and Q2, we might still use T1 to allow for punning.

Q4. Orthogonal issue: Allow B to support streamed parsing

Regardless of our choices for the other issues, we might use B to make the ontologies parsable in the streaming mode.

I am open to comments on this. Perhaps we could have a preliminary vote on this at the next telco.


Received on Saturday, 15 December 2007 20:18:04 UTC

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