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Re: Demo SPARQL notes

From: Chris Mungall <cjm@fruitfly.org>
Date: Tue, 17 Apr 2007 07:54:50 -0700
Message-Id: <897E172B-DBAC-4C8F-B4CC-E65EEF0154BD@fruitfly.org>
Cc: public-semweb-lifesci@w3.org
To: Alan Ruttenberg <alanruttenberg@gmail.com>


Looking at "Creating class level relations for easier querying of the  
GO"

The problem you are solving is the one of limited inferencing in RDF  
engines; in particular, queries such as:

SELECT *
WHERE
  {
    ?whole rdfs:subClassOf ?sub.
    ?sub rdf:type owl:Restriction.
    ?sub owl:onProperty <http://purl.org/obo/owl/part_of>.
    ?sub owl:someValuesFrom ?part.
  }

are (1) awkward to express and (2) do not take into account the  
declared transitivity of part_of, thus returning incomplete answers.

It seems that (1) is just the price you pay for the RDF-OWL  
combination. However (2) is a major problem with most existing  
triplestores.

Your solution is to insert relations at the class level, such that  
you can query:

select *
where
  {
    ?whole <http://purl.org/obo/owl/part_of> ?part.
    ?whole rdfs:label ?wlabel.
  }

This certainly helps with (1) - you don't explicitly say, but I am  
guessing that you get support for (2) through basic RDFS transitivity  
that comes for free with virtuoso?

I actually like your solution, but I would have thought the OWL  
purists would have disliked it, even with the punning caveat. It is  
compatible with the OBO relations view of the world, in which  
relations can be said to hold between types by virtue of their  
corresponding instances; and you don't have to worry about the  
inforation loss re existential restrictions since this is essentially  
built in to the relation.

It does seem like a limited trick unless you get some of the OWL  
semantics from this alternate layering onto RDF - for example, how  
would you handle instantiation?


On Apr 16, 2007, at 10:31 PM, Alan Ruttenberg wrote:

>
> I've started a page where I and others can document some of the  
> SPARQL queries and techniques that are being explored as we  
> progress towards the demo.
> The intention is to have a place to record things that are learned  
> for later reference.
>
> http://esw.w3.org/topic/HCLS/HCLSIG_Demo_QueryScratch
>
> Regards,
> Alan
>
>
>
Received on Tuesday, 17 April 2007 14:55:09 GMT

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