- From: Richard Cyganiak <richard@cyganiak.de>
- Date: Thu, 2 Apr 2015 21:27:58 +0100
- To: Arthur Ryman <arthur.ryman@gmail.com>
- Cc: "public-data-shapes-wg@w3.org" <public-data-shapes-wg@w3.org>
Arthur, I personally don’t see a problem with shapes being classes, but there is significant opposition to this notion from parts of the WG. I tried to paraphrase some of the justifications mentioned in the issue description. Richard > On 2 Apr 2015, at 21:20, Arthur Ryman <arthur.ryman@gmail.com> wrote: > > Richard, > > Thx. I believe that OWL needed to introduce punning because in strict > Description Logic there is a partitioning of resources into disjoint > sets, i.e. Class, Property, Individual. > > I don't believe that we are basing SHACL on DL. Therefore there is no > problem with SHACL triples having a their subject as a Class. Is there > some problem with this? What am I missing? Do you imagine that a SHACL > engine would need some way to distinguish a Shape from a Class? i.e. > given an IRI, if it's a Class to one thing else if it's a Shape do > some other thing? > > -- Arthur > > On Thu, Apr 2, 2015 at 4:00 PM, Richard Cyganiak <richard@cyganiak.de> wrote: >> >> >>> On 2 Apr 2015, at 20:44, Arthur Ryman <arthur.ryman@gmail.com> wrote: >>> >>> I am not familiar with the term "punning" in this context. Have you >>> got a reference? Thx. >> >> Arthur, >> >> In logic, “punning” means to use the same name for multiple distinct things. In our context, it means using the same IRI for multiple distinct things. I’m only familiar with the concept through its use in OWL 2, where a single IRI can denote multiple things, for example a class and an individual. So I don’t have any deeper background references to offer, but the examples here should be enlightening: >> >> http://www.w3.org/TR/owl2-new-features/#F12:_Punning >> >> In the context of SHACL, a punning approach would mean that classes and shapes are still conceptually distinct, but SHACL authors could use a single IRI to refer to both a class and a shape. Informally stated, I could dangle some subClassOf triples and some sh:constraint triples off the same RDF node. The semantics of SHACL would have to be carefully written to tease apart these separate aspects, so that the RDFS-related mechanisms and the SHACL-related mechanisms don’t trip each other up. >> >> Best, >> Richard >> >> >> >> >>> >>> -- Arthur >>> >>> On Sat, Mar 28, 2015 at 4:14 PM, RDF Data Shapes Working Group Issue >>> Tracker <sysbot+tracker@w3.org> wrote: >>>> shapes-ISSUE-23 (punning): Shapes, classes and punning [SHACL Spec] >>>> >>>> http://www.w3.org/2014/data-shapes/track/issues/23 >>>> >>>> Raised by: Richard Cyganiak >>>> On product: SHACL Spec >>>> >>>> Some people want to apply different shapes to the same class. >>>> Some peope want to apply shapes to data that doesn't include type statements. >>>> Some people want to associate shapes directly with class definitions. >>>> Some people want to “inherit” shapes down existing class hierarchies. >>>> Some people want to “specialise” shapes where there are no existing class hierarchies. >>>> Some people don't want shapes to have anything to do with classes at all to avoid reinventing RDFS, badly. >>>> >>>> No proposal seems to satisfy all people. >>>> >>>> >>>> >>> >>
Received on Thursday, 2 April 2015 20:28:23 UTC