[BLD] datatype support: bringing more in line with RDF and OWL, and making it more extensible

Dear all,

There are currently some discrepancies between the definition and
treatment of datatypes in RIF on the one hand, and in RDF and OWL on the
other.
Furthermore, the set of data types supported by RIF (BLD) is fixed,
which effectively means that values of datatypes not supported by RIF
cannot be exchanged, even if both partners in the exchange support the
datatype.

To amend this situation, I propose to define satisfaction and entailment
relative to a datatype map [1], which is a mapping from URIs to datatypes.
In RDF D-entailment, each datatype map is required to include
rdf:XMLLiteral, and in OWL each datatype map is required to include
rdf:XMLLiteral, xsd:string, and xsd:integer. In RIF we could require
each datatype map to include all datatypes which are currently marked as
supported.

I propose to include appropriate conditions on interpretations for
interpreting typed constants which are recognized by the datatype map.

This would have the following advantages:
- datatype support is more extensible
- we are more in line with the treatment of datatypes in other semantic
Web standards
- the definitions will be more clear and more concise


If you agree to this approach, then I can propose updated text for the
document.


Best, Jos

[1] http://www.w3.org/TR/rdf-mt/#defDatatypeMap
-- 
Jos de Bruijn            debruijn@inf.unibz.it
+390471016224         http://www.debruijn.net/
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