Re: shapes-ISSUE-40 (Property Cardinality): sh:min/max constrains properties, not values

Thanks, Holger. I'll mark this as resolved. - kc

On 4/6/15 9:40 PM, Holger Knublauch wrote:
> On 4/7/2015 13:59, Karen Coyle wrote:
>> Oh, now I think I get it. Holger, you are describing this in terms of
>> the result of a SPARQL query, right? You query on the property, and
>> count the number of objects that are returned? and that tells you how
>> many triples with that property exist?
>
> Counting triples is not a just SPARQL operation but can be done with any
> RDF based system, but yes, COUNT is also a SPARQL aggregation which is
> similar to its SQL equivalent. I introduced the term "object" because in
> the small table underneath the sentence I had to write something like
> sh:minCount "The minimum number of objects". I have no good idea how
> else to write this and welcome better proposals. For now I have changed
> it to:
>
> https://github.com/w3c/data-shapes/commit/2c1588ffc0a79ae12d06233b18cc174737f277fa
>
> The properties|sh:minCount|and|sh:maxCount|restrict the number of
> triples with thefocus nodeas thesubjectand the given property as
> thepredicate.
> Property  Value Type  Summary
> |sh:minCount|  |xsd:integer|  The minimum cardinality. Optional. Default
> value is 0.
> |sh:maxCount|  |xsd:integer|  The maximum cardinality. Optional. Default
> interpretation is unlimited.
>
>
> Holger
>
>
>>
>> That is probably what confused me, because it isn't clear from the
>> language that a query is assumed. I'll let others weigh in, but I
>> would rather that we not assume query functionality, so I'd go for
>> "count the number of triples with the focus node as the subject and
>> the given property as the predicate."
>>
>> kc
>>
>> On 4/6/15 8:20 PM, Karen Coyle wrote:
>>>
>>>
>>> On 4/6/15 7:00 PM, Holger Knublauch wrote:
>>>> I have attempted to clarify this via
>>>>
>>>> https://github.com/w3c/data-shapes/commit/1ffa8cd3225d2cc340ae3883abd5411913d7a7d4
>>>>
>>>>
>>>>
>>>>
>>>> Please let me know if this helps. I had started to use the term "value"
>>>> because I thought that "object" is less clear to newcomers who are not
>>>> too familiar with RDF technology. Yet for a formal spec, using the term
>>>> "object" may indeed be less objectionable.
>>>
>>> Sorry, Holger, trading "object" for "value" doesn't help -- my confusion
>>> was something else.
>>>
>>> What exactly is being constrained in:
>>>
>>> "The properties sh:minCount and sh:maxCount restrict the number of
>>> objects in triples with the focus node as the subject and the given
>>> property as the predicate"
>>>
>>> I think what you are saying is that you are restricting the number of
>>> times a particular predicate can appear in the focus node. Right?
>>> Because this is listed as a property constraint. Where do the objects
>>> come into that if this is a constraint on the propert(y/ies)? It's the
>>> "objects in triples" that throws me off -- number of objects in a triple
>>> is 1, right? So clearly I'm not reading this with the meaning you intend
>>> to convey.
>>>
>>> kc
>>>
>>>>
>>>> Holger
>>>>
>>>>
>>>> On 4/6/2015 2:08, RDF Data Shapes Working Group Issue Tracker wrote:
>>>>> shapes-ISSUE-40 (Property Cardinality): sh:min/max constrains
>>>>> properties, not values
>>>>>
>>>>> http://www.w3.org/2014/data-shapes/track/issues/40
>>>>>
>>>>> Raised by: Karen Coyle
>>>>> On product:
>>>>>
>>>>> The spec at https://w3c.github.io/data-shapes/shacl/ currently reads:
>>>>>
>>>>> "The properties sh:minCount and sh:maxCount restrict the number of
>>>>> values of the given property at the focus node."
>>>>>
>>>>> It should read:
>>>>> "The properties sh:minCount and sh:maxCount restrict the cardinality
>>>>> of properties of the focus node."
>>>>>
>>>>> The cardinality of the value of a triple is always min=1 max=1. It is
>>>>> the cardinality of the properties in the node that can be constrained,
>>>>> e.g.
>>>>>
>>>>> sh:property [
>>>>>         sh:predicate foaf:name ;
>>>>>         sh:minCount 1 ;
>>>>>         sh:maxCount 1 .
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>
>

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

Received on Tuesday, 7 April 2015 14:33:34 UTC