Re: the rationale and history of RDF-star semantics

The technical report published in arXiv about RDF* 
(https://arxiv.org/abs/1406.3399) in 2014 (revised 2019 then 2021) does 
say that embedded triples are syntactic sugar for RDF reification 
(section 3.2), although it does not use the phrase "syntactic sugar".

--AZ

Le 19/01/2023 à 02:32, Peter F. Patel-Schneider a écrit :
> How far does this history go back?  Wasn't the original semantics for 
> RDF* a semantics that treats embedded triples as syntactic sugar for RDF 
> reification?
> 
> 
> peter
> 
> 
> 
> On 1/17/23 08:35, Pierre-Antoine Champin wrote:
>> Dear Enrico, all,
>>
>> following the discussion we had during the last call [1], I would like 
>> to give a more detail overview of our rationale when designing the 
>> RDF-star semantics in the CG report [2], and defuse a few 
>> misunderstandings.
>>
>> 1. It was not the intention to make RDF-star a modal logic
>>
>> I know that examples such that ":alice :belives << :s :p :o >>." 
>> strongly point in the direction of modal logic, and that such examples 
>> have been largely used to "sell" RDF-star. I agree that such examples 
>> are misleading, and we actually tried to avoid such examples in the CG 
>> report.
>>
>> The intention was to make RDF-star quoted triples opaque, and 
>> providing as little inferences as possible -- leaving it open for 
>> semantic extensions to provide more inferences.
>>
>>
>> 2. Ground quoted triples are similar to literals
>>
>> Our initial attempt was to define from scratch a model theoretic 
>> semantics of RDF-star, where ground quoted triples (i.e. quoted 
>> triples containing no blank node) were constrained to denoted 
>> themselves. In other words, we consider that RDF(-star) triples (as 
>> defined by the specification) are conceptual objects that exist in the 
>> world (in the same way that graphs, classes and properties exist), and 
>> that ground quoted triples did denote exactly them.
>>
>> In that sense, ground quoted triples are very much like literals 
>> (except that they are allowed in the subject position).
>>
>>
>> 3. Blank node rain on our parade (as they usually do)
>>
>> Of course, things get tricky when we take blank nodes into account.
>>
>> Just like the RDF1.1 Semantics, our proposal was built in two steps :
>> - define the semantics of ground RFD-star graphs (following the 
>> rationale described above)
>> - deal with blank node
>>
>> The second step was quite complicated, and it raised some questions 
>> about whether this brand new semantics was sound. An alternative way 
>> was therefore proposed, to rely on the battle-tested RDF semantics. 
>> And that's where we are now.
>>
>> Honestly, I would rather give another try at /adapting /the current 
>> RDF semantics to take into account quoted graphs, than keeping the 
>> layered approach that we currently have.
>>
>>   pa
>>
>>
>> [1] https://www.w3.org/2023/01/12-rdf-star-minutes.html#t03
>> [2] https://www.w3.org/2021/12/rdf-star.html#rdf-star-semantics
>>

-- 
Antoine Zimmermann
École des Mines de Saint-Étienne
158 cours Fauriel
CS 62362
42023 Saint-Étienne Cedex 2
France
Tél:+33(0)4 77 49 97 02
http://www.emse.fr/~zimmermann/

Received on Thursday, 19 January 2023 17:05:26 UTC