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Re: RDF semantics draft revision

From: Peter Patel-Schneider <pfpschneider@gmail.com>
Date: Fri, 1 Mar 2013 13:08:19 -0800
Message-ID: <CAMpDgVyQoSePsj=3S-JjHmKxuQGETt9DEVUvTJM1Kg-cGviaJw@mail.gmail.com>
To: Pat Hayes <phayes@ihmc.us>
Cc: RDF WG <public-rdf-wg@w3.org>
Comments on 1 Mar version of RDF 1.1 Semantics


Issues to be fixed:
- make rdf:langString a regular datatype
  - unusual - empty L2V
  - only special casing is then interpretation of language-tagged strings
- elements of datatypes in RDF
  - better constraint
- add value spaces into datatype exposition


"s, p and o are in V," -> ""

"rules given above for names" -> "rules given above for ground graphs"

"1. the IRIs and literals ... refer to actual things"  doesn't make sense,
as IRIs always refer and is the number 3 an actual thing

"2. string literals ..." too early and doesn't make sense

"3. ... actual things" doesn't make sense, e.g., what about unicorns?

An RDF graph is true when
1. all literals in it refer to things
2. there is some way of interpreting the blank nodes in the scope as things
3. the IRIs in property position refer to properties, i.e., binary
relationships
4. and ...


rdf:langString may end up having an L2V map

"normatively" is no better than "conventionally" but the following text is
fine, replace this sentence with
"D-interpretations MUST interpret any datatype IRI in Concepts Section 5 as
described there."

if rdf:langString is given a trivial L2V, then "every other IRI" can be
simplified

It is not the case that a bigger D produces more entailments, at least not
in the way stated.  The datatypes corresponding to the datatype IRIs might
change.  In fact, it is possible for a datatype IRI to denote different
datatypes in different interpretations during entailment.

If rdf:langString gets the right value space, then rdf-D-interpretation can
be simplified

The treatment of datatypes is strange in RDF.
The elements of the datatype are not closed off, so, for example, "ss" could
belong to I(xsd:string), correct would be
"for every IRI aaa in D, <vvv,I(aaa)> is in IEXT(I(rdf:type)) iff vvv is in
the value space of I(D)"
although there is no mention that datatypes need a value space

well-typed is not defined anywhere

There is no xsd:number datatype!

"nnn"^^xsd:decimal is an ill-typed literal, so the entailment does not hold.

IL(E) in LV for well-typed literals is redundant, because datatypes are
subclasses of rdfs:Literal

with the change above to fix datatypes in RDF, class extensions of datatypes
are not required to be constrained by the RDFS semantic conditions

it is the case that the image of the lexical space under the L2V mapping for
a datatype is in the class extension of the datatype, but it is *not* the
case that the two are equal!

Not all triples of the form xxx rdf:type rdfs:Resource are true in all
interpretations!  "ss"^^xsd:integer rdf:type rdfs:Resource is not true in
any {xsd:integer}-interpretation.
Received on Friday, 1 March 2013 21:08:47 GMT

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