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Re: Imports issue

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Thu, 20 Feb 2003 10:01:32 +0000
Message-ID: <3E54A77C.1070202@hpl.hp.com>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
CC: schreiber@swi.psy.uva.nl, www-webont-wg@w3.org, ijd@hplb.hpl.hp.com

I agree with Peter.

Jena  has implemented daml:imports for ages now (well over a year).
It is limited to what fits in memory (with Jena's somewhat profligate 
approach to memory).

I am unsure as to whether it implements the transitive closure as specified 
  for OWL - i.e. if it is robust against import cycles.
I am copying Ian Dickenson, the developer of that code: Ian please can you 
comment (to the webont list) on how far or close it is from the OWL imports 
mechanism.
Peter outlines the OWL algorithm below.

Ian is working on OWL support for Jena2, and I understand that we intend to 
continue to support imports.

As an aside - I think imports is a much more important feature in OWL Lite 
and OWL DL than in OWL Full.

Jeremy



Peter F. Patel-Schneider wrote:

> From: Guus Schreiber <schreiber@swi.psy.uva.nl>
> Subject: IImports issue
> Date: Thu, 20 Feb 2003 00:26:57 +0100
> 
> 
>>I'm feeling increasingly uncomfortable about our "imports" resolution 
>>(see the discussion threads cited in the agenda).
>>
>>Unless we get in the very near future clear evidence this is an 
>>implementable language feature, I will have to reopen this issue and 
>>propose to give imports the same informnal status as the versioning stuff.
>>
> 
> Huh?  
> 
> To implement imports, it suffices to modify an RDF/XML processor as
> follows:
> 
>    Whenever an imports triple is found, first check to the if the object of
>    the triple has been imported already.   If not, get the document that is
>    pointed to by the object of the triple and run it through the RDF/XML
>    processor.  Then merge the result with the current graph.  Only a very
>    small amount of care is required to prevent loops.
> 
> What could be easier?
> 
> What is currently being argued about is how imports interacts with OWL Lite
> and OWL DL, i.e., what documents containing imports count as an OWL Lite or
> OWL DL document.
> 
> 
>>Note that responses of the type "this is a useful/necessary feature" are 
>>not helpful at this point. 
>>
> 
>>If we cannot show that imports  can be 
>>implemented, we will not be able to go to Proposed Rec with the OWL spec 
>>as it stands. 
>>
> 
> This is crazy!  Who has claimed that imports is not implementable!
> 
> 
>>We would all hate toi see that happen.
>>
>>Guus
>>
> 
> peter
> 
> 
Received on Thursday, 20 February 2003 05:01:53 GMT

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