Re: From syntactic to interpreted triple

> On 21. Jan 2021, at 16:43, Pierre-Antoine Champin <pierre-antoine.champin@ercim.eu> wrote:
> 
> +1 to what Olaf wrote below.
> 
> As an example, I used Jos' implementation of RDF* in EYE, and William Van Woensel super-nice N3 editor, to illustrate this with a small example:
> 
>     http://ppr.cs.dal.ca:3002/n3/editor/s/j7yBphsy
> 
> In this example, I have two predicates that link files to triples:
> 
> * :contains keeps referential opacity (nothing to do)
> 
> * :entailsForMe has some form of referential transparency (implemented through N3 rules: any triple with the same meaning as one contained in the file is also entailed for me by that file)
> 
> By running it in EYE (click "execute"), you can see that the conclusions contain:
> 
>   :report :contains <<:superman :can :fly>>.
>   :report :entailsForMe <<:superman :can :fly>>.
>   :report :entailsForMe <<:clark :can :fly>>.
> 
> but NOT
> 
>   :report :contains <<:clark :can :fly>>.

Paraphrasing James’ question to Olaf: how would you do that in SPARQL?

Thomas

> On 21/01/2021 15:35, Olaf Hartig wrote:
>> Hi Thomas,
>> 
>> You are raising an interesting point that I was also thinking about recently,
>> and I believe I have a solution.
>> 
>> First of all, regarding terminology, our groups' earlier discussions related
>> to this topic used the terms "referential opacity" and "referential
>> transparency" for what you call "syntactic triple" and "interpreted triple"
>> now.
>> 
>> The proposed semantics adopts referential opacity. From my understanding, in
>> comparison to a semantics that adopts referential transparency, adopting
>> referential opacity (as in the proposed semantics) is less restrictive in the
>> sense that it does not rule out the possibility to use referential
>> transparency for selected cases. In other words, by using referential opacity
>> as a basis (i.e., for the semantics of RDF*), on top of this basis you may
>> still define specific cases for which the additional nested triples may be
>> derived that you would expect under referential transparency. In contrast, if
>> referential transparency is used as a basis, which says that such additional
>> nested triples can be derived for all cases, then it is not possible to define
>> on top of this basis that there are cases for which the additional triples
>> should actually not be derived. At least, that's what I had understood from my
>> discussions with Pierre-Antoine and Dörthe (please feel free to confirm or
>> correct me on this).
>> 
>> Given this understanding, you may indicate the cases in which you want to use
>> referential transparency on top of a referential opacity semantics by using
>> specific properties that you introduce for this purpose. For instance, you may
>> introduce a property denoted by the URI ex:statedBy and define that
>> referential transparency can be used for nested triples that have this
>> property in their predicate position. This way, related to your example, if
>> you have a nested triple
>> 
>> <<:cars :are :bad>> ex:statedBy :Alice
>> 
>> you can derive the following triple.
>> 
>> <<:automobiles :are :bad>> ex:statedBy :Alice
>> 
>> So, while the semantics of RDF* adopts referential opacity, you can build on
>> it and define cases in which you want to have referential transparency.
>> 
>> Best,
>> Olaf
>> 
>> 
>> On torsdag 21 januari 2021 kl. 13:40:56 CET thomas lörtsch wrote:
>>> [I hope I’m using the right terminology in the right way. Advice is
>>> welcome.]
>>> 
>>> The proposed semantics defines that the embedded triple refers to a triple
>>> on the syntactic level, not in the realm of interpretation. In defense of
>>> this rather peculiar arrangement Pierre-Antoine and Dörthe argued that
>>> going from the syntactic to the interpreted triple is always possible
>>> whereas the other way round it is not: once a triple is part of the
>>> interpretation we can not know what its original syntactic structure was.
>>> That’s true (at least in any normal setup) but let's assume I’d like to
>>> annotate not the syntactic triple but the interpreted triple. What would I
>>> actually have to do to construct a reference to an interpreted triple from
>>> an RDF* embedded triple?
>>> 
>>> 
>>> Lets for example assume someone published the triple
>>> 
>>>  :cars :are :bad .
>>> 
>>> As he published that statement on the semantic web we can assume that his
>>> intend was to refer not only to :cars but just as well to :automobiles,
>>> :voitures etc. Now if we want to comment on that general interpretation of
>>> this statement, irrespective of the concrete vocabulary used, irrespective
>>> of any syntactic specifics, how would we do that? The proposed semantics of
>>> 
>>>  << :cars :are :bad >> :a :disputedClaim .
>>> 
>>> doesn’t cover this very common case as the embedded triple only refers to
>>> that very specific syntactic form. From this RDF* statement we couldn’t
>>> infer that
>>> 
>>>  << :automobiles :are :bad >> :a :disputedClaim .
>>> 
>>> even if we were using a reasonably complete mapping of car related
>>> vocabiularies. Adding all those derivable embedded triples to the database
>>> is not a viable option as it would increase operational costs enormously.
>>> We need a way to derive a reference to the interpreted triple from the
>>> syntactic triple that the RDF* embedded triple represents. But how?
>>> 
>>> 
>>> Thomas
>> 
>> 
>