Re: RDF lists/arrays and n-ary relations [was Re: OWL and RDF lists]

On 10/1/22 13:40, Nicolas Chauvat wrote:
> Le Sat, Oct 01, 2022 at 09:52:06AM -0400, Peter F. Patel-Schneider a écrit :
>> Along these lines, I wrote a long message describing several ways of
>> representing information in RDF graphs.  This response nicely illustrates
>> one of the points I am trying to make so I'm using it as, perhaps, a TL;DR
>> for my message.
> Thank you for this long explanation.
>
> I understand you are saying we have to chose between:
>
>     :marty :driveTo [ a :TZDateTime, :date "1985-10-26", :time "09:00", :tz "EST" ] .
>
> and
>
>     :marty :driveTo "1985-10-26 09:00 EST"^^:TZDateTime
>
> but should not long for something like
>
>     :marty :driveTo ("1985-10-26", "09:00", "EST")^^:TZDateTime
>
> because if it has a structure, this structure is expected to be
> described using a class or a datatype.
>
> Am I following you correctly ?

I'm saying that there already are methods for representing entities in RDF, be 
they atomic or structured.  Use them.

>
> But does not the TZDateTime datatype imply that the string has a structure ?
>
> When I will read "e1"^^:ChessPosition I will need to split the string
> in two if I want to access the rank and the file separately.
>
>> A disadvantage of the datatype route is that a particular RDF system
>> mignt not implement the chess:position datatype.
> What does it mean for a RDF system to "implement" the chess:position datatype ?

Just what it means for an RDF system to implement xsd:integer. The system has 
to recognize valid ("045") and invalid ("23skidoo") lexical forms for the 
datatype.  The system has to be able to detect when two lexical forms map to  
the same value  (as do "045" and "45").

>
> PS: I can live with defining classes or (de)serializers for every
> value I want to share using RDF, I am just trying to understand what
> are the design decisions that led to this situation and I wonder if
> these specificities of the RDF model are not hurdles to a wide adoption
> by the crowd of developers.
>
Well, yes, the principles underlying RDF do pose a burden to developers.  My 
view is that this is an inevitable consequence.


peter

Received on Saturday, 1 October 2022 20:49:50 UTC