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Re: agenda, 12 Sept, 14:30 UTC

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Tue, 12 Sep 2006 15:09:04 +0100
Message-ID: <4506BF80.9000209@hp.com>
To: Kendall Clark <kendall@monkeyfist.com>
CC: dawg mailing list <public-rdf-dawg@w3.org>

Hopefully a report will speed the telecon up (sorry - it's a bit rushed)

ARQ implementation reports and current HP position statements:

(Positions subject to change)

> 3. nonLiteral Value Testing
> 
> http://lists.w3.org/Archives/Public/public-rdf-dawg/2006JulSep/0199.html
> http://www.w3.org/2001/sw/DataAccess/issues#nonliteralValueTesting

 >>>> ILLFORMED LITERAL TESTING

ARQ implements:

datatype("-5"^^xsd:positiveInteger) = xsd:positiveInteger

xsd:positiveInteger("-5") => error

datatype is an accessor (like str() and lang())

datatype("<"^^rdf:xmlLiteral) => rdf:xmlLiteral

[[ Discussion:
Arguably that's wrong, but rdf:xmlLiteral is not required datatype in SPARQL. 
  As rdf:xmlLiteral must be exclusively canonicalized
(http://www.w3.org/TR/rdf-concepts/#section-XMLLiteral)
they require an XML parser.
]]

ARQ treats "-5"^^xsd:positiveInteger is an RDF literal (informally, think of 
RDF literal as the super type of all literals).

Position:  No change to the design of datatype.

 >>>> NON LITERAL VALUE testing

Postion:
 >>>> 1) Restrict value testing to data values with literal form

is fine if the reading for "value testing" applies to value comparison 
operations "<" and ">".  "=" works as sameTerm on non-literal forms.

"abc"^^xsd:integer = "abc"^^xsd:integer ==> true

FILTERs and non-value functions still apply to non-literals (like IRIs) and 
literals which are invalid by datatype entailment.


http://lists.w3.org/Archives/Public/public-rdf-dawg/2006JulSep/0139.html
"""
I suspect most people expect that
if I put ^^xsd:integer in there that i get an object that is an
integer!
"""

In ARQ, "abc"^^xsd:integer is an RDF literal which does not have an integer value.

> 4. contradictoryKB
> 
> http://www.w3.org/2001/sw/DataAccess/issues#contradictoryKB
> http://lists.w3.org/Archives/Public/public-rdf-dawg/2006JulSep/0119.html

Proposal:
   Entailment regimes define what is (in)consistent.
   SPARQL does not define what happens to query on an inconsistent graph

Rational: It would ideal to define what happens but the case of wanting to 
find illegal literals in a graph compared with allowing extensibility to 
reasoner-backed datasets means that one design will not cover all cases.

> 
> 5. formsOfDistinct
> 
> http://lists.w3.org/Archives/Public/public-rdf-dawg/2006JulSep/0200.html
> http://www.w3.org/2001/sw/DataAccess/issues#formsOfDistinct

HP position:

Two different solutions in a DISTINCT result set differ by one or more 
bindings.  One binding is different from another if they refer to different 
variables or the values are RDFterm-different.  DISTINCT is term-DISTINCT as 
defined for SPARQL (simple entailment).

> 
> 6. unbound variables in FILTER
> 
> http://lists.w3.org/Archives/Public/public-rdf-dawg/2006JulSep/0206.html

Acceptable.

[[
My preference is that functions can see unbound variables - each function then 
decides what to do.  ARQ provides, for debugging:

FILTER(:print(?x))

prints the value of ?x or "unbound" and returns true.
]]
Received on Tuesday, 12 September 2006 14:09:35 GMT

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