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Re: Deep copy

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Mon, 26 Sep 2016 08:46:35 -0700
To: Holger Knublauch <holger@topquadrant.com>, Dimitris Kontokostas <kontokostas@informatik.uni-leipzig.de>
Cc: "public-rdf-sha." <public-rdf-shapes@w3.org>
Message-ID: <b7ebebe2-9aca-52f6-f52e-2c416462cf69@gmail.com>
Equivalent is undefined here.

I'm assuming that the idea is to copy the list structure that makes up the
SHACL path, but not other structure.  However, at this time it is not possible
to define what this should be because the definition of SHACL paths has gaping
holes.

It is up to the working group to come up with workable definitions for such
important parts of SHACL.

Peter F. Patel-Schneider
Nuance Communications

On 09/25/2016 11:59 PM, Holger Knublauch wrote:
> I have made another attempt at this sentence:
> 
> The value of <code>sh:path</code> of each validation result must point to a
> <a>SHACL property path</a> that <a href="#path-syntax">represents</a> an
> equivalent path like the one provided in the constraint.
> 
> Is that any better? If not, can you suggest better wording?
> 
> Holger
> 
> 
> 
> On 25/09/2016 7:35, Peter F. Patel-Schneider wrote:
>> I'm assuming that you mean
>>
>> The value of sh:path of each validation result must point to a SHACL property
>> path that is identical to the path provided in the constraint.
>>
>> This is actually worse.  Identical is not defined at all in the SHACL document
>> and there is no pointer to an external meaning.  There is no useful guidance
>> to be found in the RDF documents either.  Falling back on general principles
>> would result in either identical nodes or identical graphs, both of which make
>> sense in an RDF setting, but neither of which are what is wanted here, I think.
>>
>> The solution that is needed is to define a notion of equivalence/identicalness
>> for SHACL property paths.  The section on property paths needs a complete
>> rewrite anyway so defining identical/equivalent SHACL property paths can be
>> part of this needed change.
>>
>> peter
>>
>>
>>
>>
>> On 09/24/2016 07:29 AM, Dimitris Kontokostas wrote:
>>> Thank you Peter,
>>>
>>> can you check if the latest version has any issues?
>>>
>>> Best,
>>> Dimitris
>>>
>>> On Fri, Sep 23, 2016 at 8:36 PM, Peter F. Patel-Schneider
>>> <pfpschneider@gmail.com <mailto:pfpschneider@gmail.com>> wrote:
>>>
>>>      Your reasoning is incorrect.
>>>
>>>      It appears that what you mean by "deep copy" is somewhat related to its
>>>      meaning in LISP.  The meaning of "deep copy" that most readers will
>>> know of is
>>>      is meaning in current object-oriented languages, where all objects
>>> reachable
>>>      by inter-object links are copied.  This would end up copying the entire
>>>      portion of the RDF graph reachable from the head list node, which is
>>> not what
>>>      is desired here.
>>>
>>>
>>>      Peter F. Patel-Schneider
>>>      Nuance Communications
>>>
>>>
>>>      On 09/22/2016 10:38 PM, Holger Knublauch wrote:
>>>      > On 23/09/2016 11:36, Peter F. Patel-Schneider wrote:
>>>      >>
>>>      >>> Deep copy
>>>      >>>
>>>      >>> "a deep copy of sh:path as its sh:path" What is "deep copy" in this
>>>      >> context?
>>>      >>>      Comment (HK): I have attempted to clarify this here:
>>>      >>
>>>     
>>> https://github.com/w3c/data-shapes/commit/d3f8f858f95b010d1f2a0e4681da203bcbfbc217
>>>
>>>     
>>> <https://github.com/w3c/data-shapes/commit/d3f8f858f95b010d1f2a0e4681da203bcbfbc217>
>>>
>>>      >>
>>>      >>>      Comment (kc): Unless "deep copy" has some pre-defined meaning
>>> that I
>>>      >> am unaware of, I would suggest dropping it and saying: The value of
>>> sh:path
>>>      >> of each validation result must copy all triples that are required
>>> by the <a
>>>      >> href="#path-syntax">SHACL well-formed path syntax rules</a>from the
>>>      >> <a>shapes graph</a> into the graph containing the validation results.
>>>      >>>      Comment (HK): The first google match of "deep copy" is pretty
>>>      close to
>>>      >> what I wanted to express, so I believe the term should be familiar
>>> to many
>>>      >> people and may be helpful for implementers. Also I had surrounded
>>> the term
>>>      >> with "...". Anyway, I have no strong opinion and let others decide.
>>>      >>
>>>      >> The extra wording is helpful.  However, "deep copy" in
>>>      >> https://en.wikipedia.org/wiki/Object_copying#Deep_copy
>>>      <https://en.wikipedia.org/wiki/Object_copying#Deep_copy> is
>>> different.  Either
>>>      >> drop "deep copy" or point to an appropriate definition.
>>>      >
>>>      > Almost every English word is somehow overloaded with multiple
>>> meanings. I
>>>      > believe your linked deep copy is quite appropriate for what I am
>>> trying to
>>>      > express. If anyone has a suggestion on how to explain this better,
>>> please
>>>      > provide a complete replacement of the sentence - just dropping the
>>> term does
>>>      > not work.
>>>      >
>>>      > Thanks,
>>>      > Holger
>>>      >
>>>
>>>
>>>
>>>
>>> -- 
>>> Dimitris Kontokostas
>>> Department of Computer Science, University of Leipzig & DBpedia Association
>>> Projects: http://dbpedia.org, http://rdfunit.aksw.org,
>>> http://aligned-project.eu
>>> Homepage: http://aksw.org/DimitrisKontokostas
>>> Research Group: AKSW/KILT http://aksw.org/Groups/KILT
>>>
> 
Received on Monday, 26 September 2016 15:47:09 UTC

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