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

Hi List,

Let's say I forget about cautiously staying out of a discussion where
I do not think I understand everything that has been said about the
difference in the semantics of lists/array/bags/sequences... and I
step in saying that it seems to me people are in fact describing
different use cases.

In the Python programming language, there is a difference between a
tuple (immutable) and a list (mutable).

Could it be that some people here advocate having tuples as objects of
RDF triples, while others state that we already have lists by using
the rdf:first and rdf:rest predicates ?

One would use a tuple for a value that is composed of several "sub-values":

  chess:whiteKing chess:atPosition ("e", "1")

and these tuples could be used as items in a list if necessary:

  chess:whiteKing chess:moves :pos1
  :pos1 rdf:first ("e", "1")
  :pos1 rdf:rest :pos2
  :pos2 rdf:first ("f", "2")
  :pos2 rdf:rest rdf:nil

My understanding is that we do not have the tuple construct in RDF and
would have to write

  chess:whiteKing chess:atPosition :pos
  :pos chess:positionLetter "e"
  :pos chess:positionNumber "1"

except that neither

  chess:whiteKing chess:atPosition :pos
  :pos chess:positionLetter "e"
  
nor

  chess:whiteKing chess:atPosition :pos
  :pos chess:positionNumber "1"

alone would make any sense, for "e" and "1" have to stick together in
a tuple for the position to exist / be defined.

Of course I could encode the position as the string "e1" but then I
would have to parse it.

Generalizing this idea would mean that for any compound value, I could
write a pair to encode/decode it to a string and write:

  my:individual my:property "SoMeEnc0d3dV4lue"^my:literaltype
  
In a way, having a definition for tuples in RDF would be equivalent to
defining a generic encode/decode (or serialize/deserialize) mechanism.

Is any of this making sense for someone else than me ? :)

-- 
Nicolas Chauvat

logilab.fr - services en informatique scientifique et gestion de connaissances

Received on Thursday, 29 September 2022 19:45:24 UTC