Re: SHACL syntax and metamodel complexity

Thanks, Peter. So I find this intriguing but don't know what it means in 
actual SHACL terms since it doesn't use SHACL properties. Could you say 
what the changes would be?

kc

On 2/24/16 10:10 AM, Peter F. Patel-Schneider wrote:
> More or less.
>
> "fillers of property p" = "those nodes that are the objects of s p o triples
> for any particular unspecified s"
>
> It may be useful to also allow inverse properties and property paths so the
> above rewrite would have to modified into something removed from actual triples.
>
> peter
>
>
> On 02/24/2016 09:53 AM, Karen Coyle wrote:
>> "fillers" = "values"?
>>
>> On 2/24/16 9:03 AM, Peter F. Patel-Schneider wrote:
>>> SHACL states property constraints in the following way
>>>
>>>     for the fillers of property ex:p
>>>     the special fillers must all belong to class ex:s,
>>>     there must be at least one,
>>>     there must be at least five special fillers,
>>>     they must all be either ex:a, ex:b, ex:c, ex:d, ex:e, ex:f, ex:d, ex:h,
>>>       ex:i, or ex:j,
>>>     there must be at most ten,
>>>     the identifiers used for them must match regular expression r,
>>>     they must all belong to class ex:c, and
>>>     there must be at most seven special fillers.
>>>
>>> but not in the following way
>>>
>>>     for the fillers of property ex:p
>>>     there must be at least one,
>>>     they must all belong to class ex:c,
>>>     there must be at most five,
>>>     they must all belong to class ex:d, and
>>>     there must be at least three.
>>>
>>> In my opinion, these features of the SHACL RDF syntax are contributing to
>>> the complexity of the SHACL metamodel and to the number of decisions that
>>> have to be made to construct the SHACL metamodel.
>>>
>>>
>>> If SHACL stated constraints in the following way
>>>
>>>     there must be at least one filler of property ex:p,
>>>     all the fillers of property ex:p must belong to class ex:c,
>>>     there must be at most five fillers of property ex:p,
>>>     all the fillers of property ex:p must belong to class ex:d, and
>>>     there must be at least three fillers of property ex:p.
>>>
>>> then the the metamodel for SHACL constraints could have just particular
>>> constraints (from the clauses above and other constraint constructs).  This
>>> would be a significant simplification of the metamodel.
>>>
>>>
>>> Even if SHACL permitted the second construction above and uniformly stated
>>> multi-part particular constraints as at the end of the following there might
>>> be significant simplifications of the metamodel
>>>
>>>     for the fillers of property ex:p
>>>     there must be at least one,
>>>     they must all be either ex:a, ex:b, ex:c, ex:d, ex:e, ex:f, ex:d, ex:h,
>>>       ex:i, or ex:j,
>>>     there must be at most ten,
>>>     the identifiers used for them must match regular expression r,
>>>     they must all belong to class ex:c, and
>>>     there must be at between five and seven fillers that belong to class ex:s.
>>>
>>>
>>> These simplifications would require changes to the RDF syntax of SHACL.
>>>
>>> peter
>>>
>>>
>>
>

-- 
Karen Coyle
kcoyle@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet/+1-510-984-3600

Received on Saturday, 27 February 2016 14:42:29 UTC