Re: [BLD] some more commments which I didn't manage to type in yesterday...

Axel,

Thanks for the comments.  Find replies in line.

> Starting off from Section 4
> 
> 1)
> "*** The working group will have to decide whether to specify compatibility with both OWL DL and Full, or with just one of the two. [...]"
> 
> Why? another option is differenct dialects for different OWL dialects.

I'm not sure what you mean with "different dialects" here.  The document
is the BLD specification, so the question is wedge which species of OWL
we define compatibility.

> 
> 
> 2) 
> 
> "For example, direct rule-based processing can be done by suitably restricting the OWL component to a so-called DLP subset."
> 
> to be fair, we should state as well:
> 
> "or restricting the rules part to e.g. DL-safe rule"

No direct rule-based processing is possible in the case of OWL DL +
DL-safe rules, and certainly not within the bounds of BLD.

> However, we should check here whether and how we interfer with the new OWL WG charter, since they were talking about such extensions.

As I understand the OWL 1.1 charter [1], rules are not in their scope.
They do expect "To help produce the RIF Working Group deliverable on
using RIF with OWL and generally avoid unnecessary difficulties for
users working with RIF and OWL in combination".

[1] http://www.w3.org/2007/06/OWLCharter

> 
> 3)
> "a) There are no requirements on the shape of the OWL DL ontology. b) RIF recommends to use only the DLP subset of OWL DL in combination with RIF; anyone wanting to go beyond this subset is on their own wrt. processing. c) RIF only defines the combination for the DLP subset of OWL DL."
> 
> Again, an alternative would be to do own dialects for these options.

But which option do we choose for BLD?

> 
> 4) Question on D-Entailment? Is that that simple-, RDF- and RDFS-entailment are parametrized with D, or D-entailment is a single separate entailment regime?

D-entailment is a single separate entailment regime, extending  RDFS
entailment.

> 
> 5) 
> "whereas RIF has a fixed number of datatypes, so it essentially has a fixed datatype map. Combinations of RIF with RDF under D-entailment are only defined for the case where D corresponds to the fixed datatype map of RIF."
> 
> I suggest to replace "fixed" by "dialect fixed datatype map" And note that the BLD
> datatype map can be extended by dialects but that "D^<dialect>" mapes need to 
> be defined by each dialect.
> 
> This maybe raises an issue for extensibility how the Datamaps are defined for a dialect...
> but well, there isn't much defined in terms of extensibility anyway so far.

This text is obsolete, since RIF no longer has a fixed list.  I will
update the document accordingly.

> 
> 6) 
> "
> A typed literal (s, u) is a well-typed literal if
>    1. u is in the domain of DRIF and s is in the lexical space of DRIF(u)
>    2. u is the URI of a symbol space defined by RIF and s is in the lexical space of the symbol space, or
>    3. u is not in the domain of DRIF and is not a symbol space defined by RIF.
> "
> 
> what is the diff betwen 1. and 2., don't they subsume each other?

RIF defines only 2 symbol spaces (rif:iri and rif:local), which are not
data types.

> 
> 
> 7) 
> "
> VU* is obtained from VU by replacing every RDF URI reference URI in VU 
> with "URI"^^rif:iri.
> "
> 
> How would we treat RDF typed literals... being typed by "rif:iri" (or "rif:text") then
> wouldn't that be ambiguous?

There is no ambiguity. RDF literals typed with rif:iri are simply
interpreted as arbitrary objects. rif:text is a well-defined datatype
which is interpreted accordingly.

> 
> 8) Is the @@ encoding within rif:text not superfluous? The last @ always 
> identifies the separation.

It is indeed superfluous. the definition of the datatype will be updated
accordingly.

> A cleaner/simpler solution would be:
> 
> Define for each lang tag an XML simple type as a subtype of rif:text
> e.g
> rif:text@en
> rif:text@de
> ...
> and use those types

It is not clear how to refer to such simple types.  Furthermore, we
would have to define a very large number of such data types.

best, Jos

> 
> 


-- 
Jos de Bruijn            debruijn@inf.unibz.it
+390471016224         http://www.debruijn.net/
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