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Re: nonmon mapping and punning

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Thu, 6 Mar 2008 04:11:05 -0500
Message-Id: <C690E2EC-D6CF-408C-AE9D-CF37C724C66E@gmail.com>
Cc: "Michael Schneider" <schneid@fzi.de>, "Web Ontology Language ((OWL)) Working Group WG" <public-owl-wg@w3.org>, "Jeremy Carroll" <jjc@hpl.hp.com>
To: Bijan Parsia <bparsia@cs.man.ac.uk>


On Mar 6, 2008, at 3:38 AM, Bijan Parsia wrote:

> On Mar 6, 2008, at 8:13 AM, Alan Ruttenberg wrote:
>
>> I thought the issue wasn't in adding or removing one triple, but  
>> rather the general truth maintenance issue. Namely you have rules  
>> that depend on certain triples existence as antecedents. You don't  
>> necessarily known when these rules fire, relative to when you need  
>> to retract a statement. If adding something causes you to retract  
>> a statement, then you want to also retract all triples that were  
>> added based on rules which had the retracted triple as antecedent.
>>
>> The mechanism you refer to below is possibly adequate to retract a  
>> triple (possibly because it isn't clear to me from the spec  
>> whether triples added by a reasoner would trigger the event). But  
>> it isn't adequate to retract the triples that were added as a  
>> result of rules that fired based on it.
>
> [snip]
>
> I'm missing something...why would non-monness in the mapping force  
> truth maintenance to be necessary? Or be any worse than any edit  
> cycle? (E.g., I add something, I delete something...I have to  
> update the classification and other cached entailments no matter what.

It's easier if you add something - you don't have to empty the cache  
and start over. (I have to admit, it seems a bit surreal to be saying  
this to you, since you know this, of course). Sure you *could*  
implement a system that after every insertion you force a complete  
reclassification. No one is saying that's not possible with Jena.  
It's just undesirable, and the mechanisms that let one avoid doing  
that are much easier to implement if the system is monotonic.

> if Jena is radically incompatible with this then it's impossible to  
> use for editing applications or any application where the data  
> might fluctuate. I can't believe that's true!  They have proposed  
> update extension to SPARQL!
>
> http://jena.hpl.hp.com/~afs/SPARQL-Update.html#sec_updateLanguage
>
> Now, SPARQL is only for graph syntax (for want of a better phrase),  
> not entailment defined, but it's hard to believe that HP's line is  
> "Don't use sparql update with any Jena model that uses inference of  
> any sort.")
>
> (I feel like I've been through this discussion before, in the past,  
> perhaps with Andy Seabourne in the DAWG times...or maybe it's just  
> deja vu.)
>
> (Perhaps Jeremy could clarify what HP thinks is going on, rather  
> than the rest of us guessing?)
>
> Cheers,
> Bijan.
Received on Thursday, 6 March 2008 09:11:23 GMT

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