- From: Irene Polikoff <irene@topquadrant.com>
- Date: Fri, 13 Nov 2015 12:02:55 -0500
- To: Arthur Ryman <arthur.ryman@gmail.com>
- CC: "public-data-shapes-wg@w3.org" <public-data-shapes-wg@w3.org>
Arthur, I think it was Einstein who is credited with saying that "everything should be as simple as it can be, but not simpler.¡± As many, I find the statement insightful and agree with it. So, I think in principle we are in agreement on this, but then there is a matter of judgement and agreement over what different people consider to be as simple as it can be. As for DL, I don¡¯t really know what it means in our context to ¡°keep within bounds of DL¡±. I see DL as a pretty complex topic and don¡¯t understand its relevance here. Are there applications for which DL is the simplest way to go and what are they? I don't have the definitive answer, but I doubt that data validation or UI description are it. If you are saying that for ease of understanding DL chosen not to have instance to also be a class and this precedence proves that such approach is "as simple as it can be, but not simpler¡±, I don¡¯t quite follow the reasoning. First, I am not certain that ease of understanding was the motivation. As I heard it, this had to do with some limitations of tableau algorithms and concerns about decidability. Second, in trying to use OWL while staying (for whatever reason) within DL, many people found this separation too limiting for their modeling. They asked for it to be removed. Further work on the algorithms found that this limitation was not necessary and it was removed. Irene On 11/13/15, 7:54 AM, "Arthur Ryman" <arthur.ryman@gmail.com> wrote: >Irene, > >As a general rule, I think we should keep the SHACL model as simple as >possible to make life easier for our target users. I think we can keep >within the bounds of DL. What is your opinion? > >-- Arthur > >On Thu, Nov 12, 2015 at 2:44 PM, Irene Polikoff <irene@topquadrant.com> >wrote: >> >> Arthur, >> >> Prior to OWL 2, OWL DL indeed had a strict limitation regarding >> disjointness of classes and individuals, but this limitation was removed >> in OWL 2 even for DL. Users wanted to be able to have the same thing as >>a >> class and an individual and further work on the tableau algorithms for >>DL >> revealed that they can cope with this. At least, this is my >>understanding >> of where things stand today. >> >> Best, >> >> Irene Polikoff >> >> >> >> >> On 11/12/15, 2:24 PM, "Arthur Ryman" <arthur.ryman@gmail.com> wrote: >> >>>Irene, >>> >>>I am referring to OWL DL. The partitioning of things into classes, >>>properties, and individuals allows you to express description logics >>>in OWL. This is a restricted style of modelling which is simpler to >>>understand and makes certain computations more tractable. >>> >>>-- Arthur >>> >>>On Thu, Nov 12, 2015 at 2:07 PM, Irene Polikoff <irene@topquadrant.com> >>>wrote: >>>> I may have mentioned this before, but in case I didn©öt, I do not >>>>believe >>>> it is correct to say that the idea behind OWL is not to allow >>>>meta-classes >>>> and to have classes, properties and individuals to be disjoint. >>>> >>>> Irene Polikoff >>>> >>>> >>>> >>>> >>>> >>>> On 11/11/15, 11:24 PM, "Arthur Ryman" <arthur.ryman@gmail.com> wrote: >>>> >>>>>I feel that people have an easier time understanding models in which >>>>>meta-classes are absent. This is the idea behind OWL and description >>>>>logic in which things are either classes, properties, or individuals. >>>> >>>> >> >>
Received on Friday, 13 November 2015 17:03:28 UTC