Kingsley, David, Michael, Pat, John M, Simon, and Matthew, (01)
These two threads raise some very serious issues. They're all related
to Pat's comment about the fourth field in RDF quads: (02)
PH
> it doesn't have a coherent semantics. (03)
KI
>> the number of SQL RDBMS tables produced by this dump should
>> go some way to shedding light on SQL RDBMS limitations in a
>> world where observations change at an ever increasing rate . (04)
DE
> Clearly someone's put a LOT of work into that effort. Very impressive. (05)
MB
> Maybe it also sheds light on the limitations of RDF in a similar way ?
> Like: Having information about 530 different things in one document/database
> is not equal to having made sense of it. (06)
DE
> while this stuff has been nicely arranged hierarchically...
> it just turns out that my collection of legacy systems:
>
> (a) mostly don't have much of an identifiable hierarchy any more (some did
> at one point, but entropy set in when deadlines & ignorance were applied),
>
> (b) what hierarchies are in my systems are not congruent with your idea of
>hierarchy. (07)
To repeat Pat's concerns in the thread on extensions and intensions, (08)
PH
> there is no way to standardize the multifarious potential uses for
> the fourth quad field. To my knowledge it has been used as a graph label,
> as an extra relational parameter, to encode a time reference, to indicate
> a source ..., and simply as an indexing mechanism inside a quad store.
> I am sure that there are others. (09)
JM
> I'm wondering if semantics is even needed for a 'quad field' that
> points to PROV data -- provenance appears to me a different level of
> discourse, actually much like xml:lang... (010)
Those are two uses of metalanguage -- and a metalanguage is Yet Another
Language (YAL). Every YAL needs semantics. (011)
It might seem too simple to require much semantics at this stage.
But one thing is certain: when you add one tiny little feature today,
somebody else will add more options tomorrow -- and later, more syntax. (012)
SS
> I don't think quads can be excluded from [official RDF], broadly construed,
> since N-Quads (and I guess TriG) are part of the RDF 1.1 batch of candidate
> recommendations. (013)
Yes, indeed. In the dim, dark, distant past (mid 1990s), Guha invented
RDF as a "simple" alternative to the very rich Cyc language. And in the
even dimmer, darker mid 1980s, CycL began as a "simple" frame language. (014)
MW
> My choice would be to use the additional element as an identifier for the quad
> (is that what you mean by reification?) This then means it can be referenced
> elsewhere to construct named graphs, add meta-data (such as provenance) etc.
> It’s also essentially how ISO 15926 works. (015)
I agree that would be useful. (016)
But as Pat said, that's just one of many uses for that field. When
people start adding uses, they scream when those uses are deprecated. (017)
The result, as David said: Entropy accumulates rapidly. (018)
SS
> I blame sparql. (019)
At least we can agree on something. (020)
John (021)
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