On Nov 28, 2013, at 12:23 AM, John F Sowa <sowa@xxxxxxxxxxx> wrote: (01)
> On 11/28/2013 12:53 AM, Pat Hayes wrote:
>> 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 (but not using PROV:
>> that usage pre-dates PROV by several years, maybe a decade),
>> and simply as an indexing mechanism inside a quad store.
>> I am sure that there are others.
>
> This is the result of designing syntax before anybody has any idea
> about what semantics and pragmatics that syntax would represent. (02)
The 'syntax' (If it even deserves that honorific) was not designed as such, but
implemented in so-called quad stores and rapidly taken up as a useful
implementation tool. Not surprisingly, it got used in a variety of ways. Then
SPARQL defined a notion of RDF dataset which contains 'named graphs', but
failed to specify that the name of a named graph actually names the graph. Then
people noticed that a set of graphs + names (IRIs) is just about the same thing
as a set of quads (and can certainly be implemented that way) and so the fourth
quad field got often called a 'graph name', but without any implication that it
was in any semantic sense the actual name of, ie referred to, the graph. In
many applications, it was being used to refer to something else. Then the whole
mess was turned over to the RDF WG to try to rationalize, but it was by that
time too late to bring any kind of rationality to it. (03)
To save readers of this list some wasted effort, it is now pointless to debate
what would be the best or most rational way to impose a meaning on the fourth
field of a quad. The RDF 1.1 WG has formally decided that it will not specify
this in any way at all. Y'all might find this draft overview of the situation
interesting: (04)
https://dvcs.w3.org/hg/rdf/raw-file/default/rdf-dataset/index.html (05)
but please don't cite it yet as it is still in draft form, being edited. (06)
Pat (07)
>
> The issues about designing compilers for translating one syntax
> to another were thoroughly analyzed and implemented in the 1960s.
> Many more studies of the practical, theoretical, and human factors
> issues about different kinds of grammars have been carried out in
> the past half century.
>
> Why is anybody still designing new kinds of syntax without any clue
> about what that syntax can or should represent?
>
> John
>
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> (08)
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