[redland-dev] RDFS/OWL and reasoning in Redland

[Richard Newman]

> All right, that is a different, butvalid point of view fromI  =

> wanted. Allowing anything to be stated with validation after the  =

> fact. Nevertheless, there does not seem to be a facility to allow  =

> for checking the validity of statements according to an ontology.  =

> What would you suggest?

That's not how the semantic web works.

You can say anything. Everything you say might cause additional  =

information to be inferred. That additional information, or the  =

statement itself, might cause your knowledge base to become  =

inconsistent. (The Semantic Web as a whole is almost certainly  =

inconsistent, if only because of Danny's cats' FOAF profiles!)

The store itself can't know which statement =97 the one already in the  =

store, the new one, or one of their logical consequences when  =

combined =97 is wrong; it could even be a flaw in one of your ontology  =

definitions. It knows only that the store was consistent, and now is  =

not.

If you wish, you could use some kind of wrapper:

(defun add-triple (triple)
   (let ((old-store (copy-store)))
     (add-triple-to-store triple)
     (when (inconsistent? store)
       (error "Store would be made inconsistent by adding this triple.")
       (replace-store old-store))))


(obviously implemented more efficiently, but you get the idea) but  =

that doesn't give you much to work with. Here's an example of why:

Store A:
Richard is a Car
People can't be Cars

Add 'Richard is a Person'. That statement, which is not intuitively  =

invalid, causes an error.

What would I suggest? Use a tool such as Schemarama, or even basic  =

queries, to check that data is there (that Person X has a birthday  =

and a name). Use a tool such as Racer to ensure that your data is  =

consistent (that Person X isn't simultaneously a Car and a Person).  =

And stop worrying about validation of your RDF.

-R


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