Re: RDF-star use cases from Amazon Neptune

On 12/5/21 3:47 PM, Peter F. Patel-Schneider wrote:
> On 12/5/21 14:08, Pierre-Antoine Champin wrote:
>> On 05/12/2021 02:46, Peter F. Patel-Schneider wrote:
>>> Although RDF is in some sense a logic, this is not really relevant 
>>> to the discussion here.
>> I still beg to differ. See below
> Whether RDF is a logic or not is not relevant here.  The kind of logic 
> that RDF employs is what matters.  It would be possible to create a 
> logic for particular PG formalism that supports a semantics-based 
> retrieval that retains counts.
>>> There is no requirement that a logic be based on sets (or set-like 
>>> graphs) instead of multi-sets (or multi-set-like graphs).
>> That's right, but RDF as a logic is.
>> Rephrasing my point below: this "restriction" of RDF is not an 
>> arbitrary choice that could be easily revised, because it is linked 
>> to the underlying semantics of RDF. Furthermore, since PGs do not 
>> have an underlying semantics, the same construct can be used with a 
>> different meaning in different contexts (e.g. some edges are 
>> considered as automatically asserted, while other edges are only 
>> asserted conditionally to some properties). So even if we changed the 
>> RDF abstract syntax to better align with the PG data model, I expect 
>> that there would still be common PG patterns that would not map well 
>> to the new RDF's semantics.
>>> SPARQL and SPARQL* do not use the logic of RDF.  They have no more 
>>> semantic commitment than retrieval from property graphs.
>> Granted. People can use RDF while totally ignoring its semantics, and 
>> still query it with SPARQL and maybe get something useful from it. 
>> But would that still be RDF? If they published this data on the web, 
>> would it be desirable that they advertise it as RDF?
> Anyone can do anything with anything.  But SPARQL and SPARQL* are are 
> official.  In my opinion, you can't analyze RDF without taking SPARQL 
> into account.  My opinion is that most uses of RDF graphs go through 
> SPARQL and thus the behaviour of SPARQL is much more important than 
> the RDF semantics.  So I would say that you can't consider RDF as 
> strictly a non-counting logic.
> This is just like the situation with relational data bases. Although 
> relational data bases are strictly defined as sets of tuples, SQL uses 
> multi-sets in some places.

Hi Peter,

What do you mean by "SPARQL* (a/k/a SPARQL-Star) has become official? 
Naturally, the same question applies to RDF* (a/k/a RDF-Star).


Kingsley Idehen 
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OpenLink Software
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Received on Monday, 6 December 2021 14:49:53 UTC