[Pellet-Users] saving the classification/realization state of a knowledgebase

[Alan Ruttenberg]

On Oct 9, 2006, at 3:48 AM, Bijan Parsia wrote:

> On Oct 9, 2006, at 6:13 AM, Alan Ruttenberg wrote:
>
>> I wonder if someone could sketch out some of the issues with saving
>> the post-classified state of a knowledgebase. If I want to work with
>> a kb that takes a while to classify/check (e.g. Galen), what
>> structures need to be saved so that I could restart, repopulate them,
>> and continue querying the KB without reclassifying.
> [snip]
> It's not primarily saving the post-classified state of a knowledge  
> base that's an issue if you intend to update the restored KB. In  
> vanilla Pellet, everything is thrown away and restarted if you  
> modify the KB. Christian, of course, is working on incremental  
> update of the KB, and has some reasonable success...dramatic  
> success with ABox update (ords of mag). We are working on TBox  
> update again.

That's very cool - looking forward to it. I've been playing around  
with productions the consequents of which update the knowledgebase,  
just toy size right now, but that could form a test case.

However, just being able to save the state, without updating, would  
be useful - for instance to be able to start up a server with an in  
memory model to make available for queries only, as in working with  
an application that uses some fixed ontology.

> He has done some work to incremental query update (in the context  
> of streaming queries), so that'll be part of the package.

I don't know what you mean by "streaming queries". By query update do  
you mean delivering incremental answers to a query that is  
registered, as the kb is updated?

> I think there is little point to serializing the structures until  
> incremental update is in place (you might save on parsing and  
> preprocessing, but eh; ok, there are times when parsing dominates,  
> but that's just morally wrong! ;)).

I agree, but it seems that it's really the time to classify/check  
consistency, realize that matters with some of the ontologies.

> Evren and I plan to evolve Pellet to using some form of secondary  
> storage directly which should also help.
>
> (There are some approximations in the above.)
>
> Of course we are approaching having incremental update in the  
> current release. I'm sure Christian would love to have some  
> examples. Also, to flip it around, once you have incremental,  
> storing state becomes quite valuable.
>
> Cheers,
> Bijan.