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Re: do bad datatype literals denote [was Re: Datatype test cases ...]

From: Jan Grant <Jan.Grant@bristol.ac.uk>
Date: Wed, 20 Nov 2002 16:23:26 +0000 (GMT)
To: Brian McBride <bwm@hplb.hpl.hp.com>
cc: pat hayes <phayes@ai.uwf.edu>, Jeremy Carroll <jjc@hplb.hpl.hp.com>, RDFCore Working Group <w3c-rdfcore-wg@w3.org>
Message-ID: <Pine.GSO.4.44.0211201616100.12073-100000@mail.ilrt.bris.ac.uk>

On Wed, 20 Nov 2002, Brian McBride wrote:

> [attribution lost - the other person is me]
>
> >NO. This is related to what Pat was complaining about. Basically, a
> >"Positive entailment test" with premise document P and consequent
> >document C passes if:
> >
> >         - P has an interpretation (ie, contains no semantic errors
> >           wrt the constraints imposed by the interpretation rules used
> >           for the test case) AND
> >         - P entails C.
> >
> >A "negative entailment test" passes if:
> >
> >         - P has no valid interpretations (contains a semantic error) OR
> >         - P is ok but does not entail C.
>
> OK, so because its a neg entailment of the empty graph, then by this rule,
> there can be no valid interpretations.  I thought the model theory had bad
> datatype lex forms denoting something though, in which case there is an
> interpretation.  Right, from 3.4 of the MT:
>
> [[For any typed literal "sss"^^ddd in G, if I(ddd) is in D and 'sss' is not
> a valid lexical form for I(ddd) then IL("sss"^^ddd) is not in LV]]
>
> and
>
> [[(this) condition requires than an 'ill-formed' typed literal, i.e. one
> where the literal string is not in the lexical space of the datatype, not
> denote any literal value. Intuitively, such a name does not denote any
> value, but in order to avoid the semantic complexities which arise from
> empty names, we requires such a typed literal to denote an 'arbitrary' value.]]
>
> Thus there are interpretations of the graph
>
>    http://www.w3.org/2000/10/rdf-tests/rdfcore/datatypes/test002.nt
>
> and the test does not work

Yech. The words that the current test case WD uses are _extremely_
woolly

[[
A premise document that contains a semantic error with respect to any
constraints imposed by the entailment rules selected will cause this
[positive entailment] test to fail.
]]

and in particular, it's the case of duff lexical forms for datatyped
literals that I wanted to cover with this. In other words, if a graph
contains datatyped literals that need to be given "arbitrary"
denotations, that's (one kind of) the "semantic error" I was alluding
to.

This clearly needs putting in better terms. If the entailement tests can
be utilised for this purpose in their current form but with better
wordsmithing, that'd be good - but clearly some better words are
required, because the definition is currently clearly lacking!

jan


-- 
jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/
Tel +44(0)117 9287088 Fax +44 (0)117 9287112 http://ioctl.org/jan/
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Received on Wednesday, 20 November 2002 11:24:26 EST

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