[DTB] value space of XMLLiteral

The value space of the rdf:XMLLiteral datatype [1] is not well defined.
It is just some arbitrary set that is isomorphic to the lexical space
and disjoint from the XML schema datatypes. This definition is
ambiguous, because it does not tell us, e.g., whether there is overlap
between this value space and the value space of rdf:text.

I see two possible solutions:
a- we define the set of all possible datatypes and require the value
space of XMLLiteral to be disjoint from all other value spaces in the set or
b- we really define the value space, e.g., as the XML info set
corresponding to the XML graph. However, I do not know enough about the
definition of infosets to say whether the mapping between XML documents
in the lexical space of XMLLiteral and the infosets is isomorphic. We
thus have three sub-options:
  b1) We assume that when people are using XMLLiteral, they actually
intend to talk about the infoset and we accept possible equalities
inferred by our definition that are not inferred by possible RDF
implementations [2].
  b2) Someone finds out whether there is any real difference [I am not
going to do this].
  b3) We define the value space in such a way that it is isomorphic to
the lexical space and disjoint from the value space of any datatype we
know of.


Best, Jos


[1] http://www.w3.org/TR/rdf-concepts/#section-XMLLiteral
[2] I actually don't know whether there is any proper implementation of
the XMLLiteral datatype, so this may be a moot point.
-- 
Jos de Bruijn            debruijn@inf.unibz.it
+390471016224         http://www.debruijn.net/
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