Re: Shapes, Individuals, and Classes - OSLC Motivations

Yes, the working group could take this approach to define the semantics of 
constraints, but there are other approaches that I believe are at least as viable.

peter


On 11/12/2014 04:59 AM, Arthur Ryman wrote:
> Peter,
>
> You are right. I reread the spec more carefully. A literal term contains
> the lexical form, not the value defined by the lexical-to-value mapping.
> Literal term equality requires that the lexical forms are equal,
> character-by-character.
>
> The consequence of this is that when we define the semantics of
> constraints we should phrase them in terms of the value space of the
> associated datatype, if that is significant. If we translate constraints
> into SPARQL then we should use the appropriate type-casting functions.
>
> Therefore we can still define the semantics of constraints in terms of the
> RDF graph, but we need to be explicit about when we are referring to the
> value space of a datatype.
> _________________________________________________________
> Arthur Ryman
> Chief Data Officer
> SWG | Rational
> 905.413.3077 (phone) | 416.939.5063 (cell)
> IBM InterConnect 2015
>
>
>
>
> From:   "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
> To:     Arthur Ryman/Toronto/IBM@IBMCA,
> Cc:     "Eric Prud'hommeaux" <eric@w3.org>, public-data-shapes-wg@w3.org
> Date:   11/11/2014 07:59 PM
> Subject:        Re: Shapes, Individuals, and Classes - OSLC Motivations
>
>
>
> You can disagree all you want, but "1"^^xsd:integer and "01"^^xsd:integer
> do
> indeed represent different nodes in any RDF graph.  To see this all you
> have
> to look at is the RDF Concepts and Abstract Syntax
> http://www.w3.org/TR/2014/REC-rdf11-concepts-20140225/ Section 3.3, which
> talks about literal term equality, and Section 3.1, which says that the
> triples of RDF objects can be literals.
>
> Neither datatypes nor the RDF model theory nor what an RDF literal
> represents
> affect this aspect of RDF graphs.
>
> peter
>
>
>
> On 11/11/2014 02:00 PM, Arthur Ryman wrote:
>> Peter,
>>
>> I disagree with your assertion that "1"^^xsd:integer and
> "01"^^xsd:integer
>> represent different RDF nodes. Please refer to [1] and [2]
>>
>> A datatype consists of a lexical space, and value space, and a
>> lexical-to-value mapping. Several strings in the lexical space may map
> to
>> the same element of the value space.  An RDF literal that includes a
>> datatype URI represents the value, i.e. the lexical-to-value mapping is
>> applied to the lexical string.
>>
>> [1] http://www.w3.org/TR/rdf11-concepts/#section-Datatypes
>> [2] http://www.w3.org/TR/rdf11-mt/#literals-and-datatypes
>> _________________________________________________________
>> Arthur Ryman
>> Chief Data Officer
>> SWG | Rational
>> 905.413.3077 (phone) | 416.939.5063 (cell)
>> IBM InterConnect 2015
>>
>>
>>
>>
>> From:   "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
>> To:     Arthur Ryman/Toronto/IBM@IBMCA, "Eric Prud'hommeaux"
>> <eric@w3.org>,
>> Cc:     public-data-shapes-wg@w3.org
>> Date:   11/10/2014 10:54 AM
>> Subject:        Re: Shapes, Individuals, and Classes - OSLC Motivations
>>
>>
>>
>> RDF graphs are defined without respect to XML datatypes.  For example,
>> "1"^^^xsd:integer and "01"^^xsd:integer are different as far as RDF
> graphs
>> are
>> concerned.
>>
>> Of course, there is a close relationship between these two literals, but
>> that
>> is (mostly) defined in the RDF semantics.
>>
>> So is it then the case that OSLC goes beyond RDF graphs?
>>
>> peter
>>
>>
>> On 11/10/2014 07:38 AM, Arthur Ryman wrote:
>>> Eric,
>>>
>>> Yes. RDF includes the built-in XML datatypes.
>>> _________________________________________________________
>>> Arthur Ryman
>>> Chief Data Officer
>>> SWG | Rational
>>> 905.413.3077 (phone) | 416.939.5063 (cell)
>>> IBM InterConnect 2015
>>>
>>>
>>>
>>>
>>> From:   "Eric Prud'hommeaux" <eric@w3.org>
>>> To:     "Peter F. Patel-Schneider" <pfpschneider@gmail.com>,
>>> Cc:     Arthur Ryman/Toronto/IBM@IBMCA, public-data-shapes-wg@w3.org
>>> Date:   11/07/2014 08:46 AM
>>> Subject:        Re: Shapes, Individuals, and Classes - OSLC Motivations
>>>
>>>
>>>
>>> * Peter F. Patel-Schneider <pfpschneider@gmail.com> [2014-11-06
>>> 20:36-0800]
>>>> So your view is that all that counts is the graph?  Nothing about
>>>> datatypes, or RDF, or RDFS?
>>>
>>> I suspect that OSLC wants datatypes, noting that Resource Shapes has
>>> an oslc:valueType predicate for identifying the datatype of a literal.
>>>
>>>      http://www.w3.org/Submission/2014/SUBM-shapes-20140211/#valueType
>>>
>>>
>>>> peter
>>>>
>>>>
>>>> On 11/06/2014 12:01 PM, Arthur Ryman wrote:
>>>>> Peter,
>>>>>
>>>>> Commenting on your proposed wording of how to express the
> "decoupling"
>>>>> requirement. I'd go further and demote the notion of class to being
>>> more
>>>>> like just another property and view the shape/constraints as applying
>>> to
>>>>> the RDF representation of an information resource, i.e. to a set of
>>>>> triples (aka an RDF graph). Some of the triples will have rdf:type as
>>> the
>>>>> predicate and those triples are useful for locating certain subject
>>> nodes
>>>>> that we want to say more things about, e.g that they are the subjects
>>> of
>>>>> triples that have certain other predicates, etc.
>>>>> _________________________________________________________
>>>>> Arthur Ryman
>>>>> Chief Data Officer
>>>>> SWG | Rational
>>>>> 905.413.3077 (phone) | 416.939.5063 (cell)
>>>>> IBM InterConnect 2015
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> From:   "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
>>>>> To:     Arthur Ryman/Toronto/IBM@IBMCA,
>>>>> Cc:     public-data-shapes-wg@w3.org
>>>>> Date:   11/06/2014 12:14 PM
>>>>> Subject:        Re: Shapes, Individuals, and Classes - OSLC
>> Motivations
>>>>>
>>>>>
>>>>>
>>>>> I still don't know what "custom" means here with respect to RDF.  As
>>> far
>>>>> as I
>>>>> can tell any bit of an ontology, or class, or property, or
> constraint,
>>> or
>>>>> shape could be called "custom".  Now it may be that within OSLC there
>>> is
>>>>> some
>>>>> notion of custom vs non-custom, but how can that notion be removed
>> from
>>>>> OSLC
>>>>> so that it can be used elsewhere?
>>>>>
>>>>> Similarly, the notions of "specification", "implementation",
>> "project",
>>>>> etc.,
>>>>> appear to me to be specific to OSLC, and particular to the design
>>>>> methodology
>>>>> you outline below, and using them to drive a spec could, I think, tie
>>> that
>>>>>
>>>>> spec quite closely to the design methodology.
>>>>>
>>>>>
>>>>>
>>>>> As a contrast, here is what I believe should be used to say that
>>> classes
>>>>> and
>>>>> shapes/constraints are decoupled.
>>>>>
>>>>> Definition:  Classes and shapes/constraints are decoupled if the
>>>>> specification
>>>>> can use different sets of shapes/constraints on the same class.  For
>>>>> example,
>>>>> if the specification permits the ontology
>>>>>       ex:Person rdf:type rdfs:Class .
>>>>>       ex:name rdf:type rdf:Property .
>>>>>       ex:name rdfs:domain ex:Person .
>>>>> to be used with the constraint set
>>>>>       ex:Person < exists ex:name
>>>>> (every person has a "known" value for its name)
>>>>> or used with the constraint set
>>>>>       ex:Person < all ex:name xsd:string
>>>>> (all "known" names of people are strings)
>>>>> then it will be said to allow the decoupling of constraints/shapes
> and
>>>>> classes.
>>>>>
>>>>>
>>>>> A stronger notion would be that shapes/constraints are independent of
>>>>> classes.
>>>>>      This could be defined as:
>>>>>
>>>>> Definition:  Classes and shapes/constraints are independent if some
>>>>> shapes/constraints do not use class membership in their definition.
>> For
>>>>> example, the following constraint is class-independent:
>>>>>       exists ex:name < exactly 1 ex:name
>>>>> (if something has a "known" name then it has exactly one "known"
> name)
>>>>>
>>>>>
>>>>> peter
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On 11/06/2014 04:59 AM, Arthur Ryman wrote:
>>>>>> Peter,
>>>>>>
>>>>>> OSLC defines specification for RDF representation of resources in
>>>>> several
>>>>>> domains, e.g. Requirements, Quality, Change Management etc. A
>>>>>> specification typically defines a class and several properties.
>>>>>> Implementations are allowed to add new RDF properties but they don't
>>>>>> necessarily introduce new RDF classes. Furthermore, within an
>>>>>> implementation, users may add custom RDF properties on a
>>>>>> project-by-project basis, but that doesn't change the RDF class.
>>>>> Therefore
>>>>>> different projects use different Shapes but the Shapes only differ
> by
>>>>> RDF
>>>>>> properties, not RDF classes. That is what I mean by decoupling
> Shapes
>>>>> and
>>>>>> Classes.
>>>>>>
>>>>>> I will elaborate this on the wiki.
>>>>>> _________________________________________________________
>>>>>> Arthur Ryman
>>>>>> Chief Data Officer
>>>>>> SWG | Rational
>>>>>> 905.413.3077 (phone) | 416.939.5063 (cell)
>>>>>> IBM InterConnect 2015
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> From:   "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
>>>>>> To:     Arthur Ryman/Toronto/IBM@IBMCA,
> public-data-shapes-wg@w3.org,
>>>>>> Date:   11/05/2014 05:27 PM
>>>>>> Subject:        Re: Shapes, Individuals, and Classes - OSLC
>>> Motivations
>>>>>>
>>>>>>
>>>>>>
>>>>>> I'm still wondering what you think it means to decouple shapes and
>>>>>> classes.
>>>>>> The first motivation you provide is supported by both SPIN and OWL
>>>>>> constraints.  I can't figure out what custom properties have to do
>>> with
>>>>>> classes, or constraints, or shapes.  The behaviour you appear to be
>>>>>> looking
>>>>>> for in your second paragraph is also supported by both SPIN and OWL
>>>>>> constraints.
>>>>>>
>>>>>> I had thought that this was ironed out at the Face-to-Face, but I
>>> guess
>>>>>> not.
>>>>>>
>>>>>> peter
>>>>>>
>>>>>>
>>>>>> On 11/05/2014 01:47 PM, Arthur Ryman wrote:
>>>>>>> There are a few motivations for decoupling shapes and classes. One
>> is
>>>>>> that
>>>>>>> the creation shape may be different than the update shape. Another
>>> has
>>>>>> to
>>>>>>> do with custom properties. I'll write up the following in the wiki.
>>>>>>>
>>>>>>> OSLC supports an open content model for resources. It is common for
>>>>>> tools
>>>>>>> to add their own custom properties, and for projects within a tool
>> to
>>>>>> have
>>>>>>> different user-defined properties. For example, consider a bug
>>> tracking
>>>>>>> tool. Project A may add a custom property foo and project B may add
>>>>> bar.
>>>>>>> All projects use the same RDF type for bug resources, e.g.
>>>>>>> oslc_cm:ChangeRequest. However, the shape for resources in project
> A
>>>>>>> differs for the shape for project B.
>>>>>>> _________________________________________________________
>>>>>>> Arthur Ryman
>>>>>>> Chief Data Officer
>>>>>>> SWG | Rational
>>>>>>> 905.413.3077 (phone) | 416.939.5063 (cell)
>>>>>>> IBM InterConnect 2015
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>>
>>
>
>
>

Received on Wednesday, 12 November 2014 13:15:00 UTC