Re: on lists

In terms of Peter’s original question, this gives something of a chicken-and-egg problem: probably resolvable with some clear English text, and later a formal definition in SHACL that actually depends on itself.

You and Peter seem to be working through the "clear English text” part

Jeremy



> On Oct 17, 2016, at 9:39 AM, Jeremy J Carroll <jjc@syapse.com> wrote:
> 
> 
> Hi Holger
> 
> on your historical issue:
> 
> 
>> On Oct 15, 2016, at 8:57 PM, Holger Knublauch <holger@topquadrant.com <mailto:holger@topquadrant.com>> wrote:
>> 
>> It is a bit surprising that there doesn't seem to be a standard definition of what a well-formed rdf:List is.
> 
> 
> Back in 2004 time-frame, the RDF group felt that it was out of scope because the ‘obvious’ constraints were simply not the sort of complex syntactical constraint at a graph level that the group felt were in scope for that group.
> If when you merge graphs, apply inferences, etc etc you get an ill-formed list, what do you do?
> i.e. the RDF Core WG was aware of the problem of ill-formed lists and made an explicit decision that it was not within the focus of the work
> 
> On the other hand, the OWL WG, were schizophrenic, with the DL/Lite versions simply regarding the triples as a projection of the real OWL syntax: in this projection all lists are well formed, but you cannot use rdf lists as a general data structure.
> In OWL Full, OTOH, constraints are expressed semantically not syntactically, and so the well-formedness constraint for RDF lists was once again out of scope.
> 
> It seems to me that this constraint is one of many potential high level syntactic constraints on RDF triples expressing data structures, and I am pleased to see that it is noted as in-scope for the shapes group:
> 
> https://www.w3.org/TR/2015/WD-shacl-ucr-20150414/#uc26-rdf-lists-and-ordered-data <https://www.w3.org/TR/2015/WD-shacl-ucr-20150414/#uc26-rdf-lists-and-ordered-data>
> 
> This, to me at least, seems to be the appropriate level at which to fix this long-standanding problem.
> 
> 
> Jeremy