Re: [External] : Can a triple-term in an N-Triple 1.2 statement have "infinite" number of atomic terms?

On 27/01/2025 16:44, Souripriya Das wrote:
> Sorry, I meant the following Turtle 1.2 statement ... (not the 
> shortcut version involving << ... >> — thanks to Pierre-Antoine and 
> Enrico for pointing this out)
>     :s1 :p1 <<( :s2 :p2  ... <<( :sN :pN  :oN )>>  ... )>> .
>
> So, can an implementation support a chosen upper limit for the depth 
> of nesting -- to say 0 (yes, even 0), 1, 2, or whatever -- for 
> triples-terms and still be conformant with RDF 1.2?
>
> Since there is no way to represent a triple involving an N-depth 
> triple-term in a triplestore that supports depth less than N, 
> interoperability of data will be affected. The following statement, 
> for example,
>      :s1 :p1 <<( :s2 :p2 <<( :s3 :p3  <<( :s4 :p4 :o4 )>> )>> )>> .
> cannot be stored in a triplestore that does not support the depth of 
> nesting needed for this statement.
>
> Pierr-Antoine wrote:
> > Note however that this is an extreme corner case, since most of the 
> time, people would make statements about reifiers rather than about 
> triple terms themselves.
>
> My concern is whether we are putting too much complexity into RDF1.2 
> to support rare situations and thereby creating potential for 
> interoperability issues.

I also wrote "Note that in theory, literals in N-Triples (and in RDF 
abstract syntax) are also unbounded (...). Yet, I assume that all 
implementations have limits on the size of the (...) literals they can 
accept.". This can also be argued to create interoperability issue. I 
think this situation is still better than arbitrarily restricting the 
size of literals allowed in RDF. The same goes for triple-term depth, IMO.

> Thanks,
> Souri.
>
> ------------------------------------------------------------------------
> *From:* Franconi Enrico <franconi@inf.unibz.it>
> *Sent:* Monday, January 27, 2025 9:13 AM
> *To:* Souripriya Das <souripriya.das@oracle.com>
> *Cc:* Pierre-Antoine Champin <pierre-antoine@w3.org>; Andy Seaborne 
> <andy@apache.org>; public-rdf-star-wg@w3.org <public-rdf-star-wg@w3.org>
> *Subject:* Re: [External] : Can a triple-term in an N-Triple 1.2 
> statement have "infinite" number of atomic terms?
> Souripriya Das  wrote:
>> So, if we go with such a "no nested triples-terms" restriction in 
>> N-Triples 1.2, conversion of the following Turtle 1.2 statement 
>> (containing a nested triple-term)
>>     :s1 :p1 <<( :s2 :p2  ... <<( :sN :pN  :oN )>>  ... )>> .
>> to N-Triples 1.2 will be the following set of statements:
>>     :s1 :p1 _:b2 .
>>     _:b2 rdf:reifies <<( :s2 :p2 _:b3 )>> .
>>               ...
>>     _:bN rdf:reiffes <<( :sN :pN :oN )>> .
>
> No. The Turtle 1.2 statement
>
>     :s1 :p1 <<( :s2 :p2  ... <<( :sN :pN  :oN )>>  ... )>> .
>
> is represented in N-Triples in the same way, since it does not make 
> use of a Turtle 1.2 shortcut.
> Therefore you need to have in N-Triples "nested triples-terms”, 
> otherwise we would not be able to capture the RDF 1.2 grammar as we 
> have decided. I expect that triples with nested triple terms will be 
> rare, just like triples with triple terms without rdf:reifies will be 
> rare; their combination will be even more rare.
> On the other hand, the Turtle 1.2 statement
>
>     :s1 :p1 << :s2 :p2  ... << :sN :pN  :oN >>  ... >> .
>
> uses a shortcut, and it is expanded in N-Triples as you say:
>
>     :s1 :p1 _:b2 .
>      _:b2 rdf:reifies <<( :s2 :p2 _:b3 )>> .
>
>         ...
>
>     _:bN rdf:reiffes <<( :sN :pN :oN )>> .
>
>
> cheers
> —e.
>
>> ------------------------------------------------------------------------
>> *From:*Pierre-Antoine Champin <pierre-antoine@w3.org>
>> *Sent:*Monday, January 27, 2025 7:36 AM
>> *To:*Souripriya Das <souripriya.das@oracle.com>; Andy Seaborne 
>> <andy@apache.org>;public-rdf-star-wg@w3.org<public-rdf-star-wg@w3.org>
>> *Subject:*Re: [External] : Can a triple-term in an N-Triple 1.2 
>> statement have "infinite" number of atomic terms?
>>
>> On 27/01/2025 13:01, Souripriya Das wrote:
>>> So, in short, N-Triples 1.2 will allow potentially "infinite"-length 
>>> statements, including ones like the following:
>>>
>>>     :s1 :p1 <<( :s2 :p2  ... <<( :sN :pN :oN )>>  ... )>> .
>> I would rather say "unbounded" (triple terms, even nested, are always 
>> finite), but yes.
>> Note however that this is an extreme corner case, since most of the 
>> time, people would make statements about reifiers rather than about 
>> triple terms themselves.
>>
>> Note that in theory, literals in N-Triples (and in RDF abstract 
>> syntax) are also unbounded; same for IRIs. Yet, I assume that all 
>> implementations have limits on the size of the IRIs and literals they 
>> can accept. So I would not be surprised or concerned if 
>> implementations also had limits on the depth of nesting that they 
>> accept...
>>>
>>> Such a statement in N-Triples 1.2 will contain 2N+1 "atomic" RDF 
>>> 1.1, possibly unique, terms in a single line (i.e., ending with EOL).
>>>
>>> Please confirm.
>>>
>>> Thanks,
>>> Souri.
>>>
>>>
>>>
>>> ------------------------------------------------------------------------
>>> *From:*Pierre-Antoine Champin<pierre-antoine@w3.org> 
>>> <mailto:pierre-antoine@w3.org>
>>> *Sent:*Monday, January 27, 2025 6:29 AM
>>> *To:*Souripriya Das<souripriya.das@oracle.com> 
>>> <mailto:souripriya.das@oracle.com>; Andy Seaborne<andy@apache.org> 
>>> <mailto:andy@apache.org>;public-rdf-star-wg@w3.org 
>>> <mailto:public-rdf-star-wg@w3.org><public-rdf-star-wg@w3.org> 
>>> <mailto:public-rdf-star-wg@w3.org>
>>> *Subject:*Re: [External] : Can a triple-term in an N-Triple 1.2 
>>> statement have "infinite" number of atomic terms?
>>>
>>> On 27/01/2025 11:36, Souripriya Das wrote:
>>>> Andy wrote:
>>>> >> That's the N-Triples that I'm getting for that Turtle example.
>>>> It does not have a nested triple term.
>>>>
>>>> That's good but just to be sure, let me tweak the Turtle 1.2 
>>>> statement a bit to avoid the use of explicit reifiers.
>>>>
>>>> Would the following statement in Turtle 1.2:
>>>>     :s :believes << :s2 :believes << :s3 :p3 :o3 >>  >> .
>>>> be a valid statement in N-Triples 1.2 as well?
>>> No, because the '<< ... >>' construct (reification) is only part of 
>>> Turtle, not of N-Triples.
>>> Not ot be confused with the '<<( ... )>>' construct (triple terms), 
>>> which is also part of N-Triples.
>>> And yes, recursive triple terms are possible, e.g.
>>>
>>>   _:b1 rdf:reifies <<( _:b2 rdf:reifies <<( <tag:s> <tag:p> <tag:o> 
>>> )>> )>> .
>>>
>>> This is valid N-Triples, and contains 1 (asserted) triple.
>>>
>>>   best
>>>
>>>>
>>>> Or, would it always require use of multiple statements in 
>>>> N-Triples, something like the following?
>>>>     :s believes _:b2 .
>>>>     _:b2 rdf:reifies <<( :s2 :believes _:b3 )>> .
>>>>     _:b3 rdf:reifies <<( :s3 :p3 :o3 )>> .
>>>> Thanks,
>>>> Souri.
>>>>
>>>> ------------------------------------------------------------------------
>>>> *From:*Andy Seaborne<andy@apache.org> <mailto:andy@apache.org>
>>>> *Sent:*Saturday, January 25, 2025 7:09 AM
>>>> *To:*public-rdf-star-wg@w3.org 
>>>> <mailto:public-rdf-star-wg@w3.org><public-rdf-star-wg@w3.org> 
>>>> <mailto:public-rdf-star-wg@w3.org>
>>>> *Subject:*Re: [External] : Can a triple-term in an N-Triple 1.2 
>>>> statement have "infinite" number of atomic terms?
>>>>
>>>>
>>>>
>>>> On 24/01/2025 17:31, Souripriya Das wrote:
>>>>> In N-Triple 1.1 syntax, a statement consists of exactly three 
>>>>> (atomic) terms and I am hoping that N-Triple 1.2 will be a simple 
>>>>> extension that will allow 5-term statements as well, subject to 
>>>>> the restriction that the predicate for such 5-term statements will 
>>>>> always berdf:reifies.
>>>>>
>>>>> Thus, the following statement in Turtle 1.2:
>>>>>     :s :believes << :s2 :believes << :s3 :p3 :o3 ~ :r3 >> ~ :r2 >> .
>>>>> will be written in N-Triple 1.2 as follows:
>>>>>   :s believes :r2 .
>>>>>   :r2rdf:reifies<<( :s2 :believes :r3 )>> .
>>>>>   :r3rdf:reifies<<( :s3 :p3 :o3 )>> .
>>>>>
>>>>> Is this aligned with the current thinking in the WG?
>>>>
>>>> That's the N-Triples that I'm getting for that Turtle example.
>>>> It does not have a nested triple term.
>>>>
>>>>>
>>>>> Thanks,
>>>>> Souri.
>>>>> ------------------------------------------------------------------------
>>>>> *From:*Souripriya Das<souripriya.das@oracle.com> 
>>>>> <mailto:souripriya.das@oracle.com>
>>>>> *Sent:*Thursday, January 23, 2025 11:59 AM
>>>>> *To:*RDF-star WG<public-rdf-star-wg@w3.org> 
>>>>> <mailto:public-rdf-star-wg@w3.org>
>>>>> *Subject:*[External] : Can a triple-term in an N-Triple 1.2 
>>>>> statement have "infinite" number of atomic terms?
>>>>> Would the following be a valid N-Triple 1.2 statement, where n can 
>>>>> be, say, 1000?
>>>>> (There will be a total of 2*1000 + 1 = 2001 "atomic" terms in the 
>>>>> triple-term used as the object.)
>>>>>
>>>>>     :s :p <<( :s1 :p1 <<( :s2 :p2 <<( ... <<(  :sn :pn :on )>> )>> 
>>>>> )>> )>> .
>>>>
>>>> The RDF Abstract Syntax allows it and N-triples has concrete syntax 
>>>> for it.
>>>> https://www.w3.org/TR/rdf12-concepts/#section-triples 
>>>> <https://urldefense.com/v3/__https://www.w3.org/TR/rdf12-concepts/*section-triples__;Iw!!ACWV5N9M2RV99hQ!JYEvlde5NuL_h5csMvH6AwkIwDQ-0an7pS64QPbyPujF1z1Hq5zPtm0_FQrFPc5jqgNd1kTb5R4zo_5x$>
>>>> https://www.w3.org/TR/rdf12-concepts/#section-triple-terms 
>>>> <https://urldefense.com/v3/__https://www.w3.org/TR/rdf12-concepts/*section-triple-terms__;Iw!!ACWV5N9M2RV99hQ!JYEvlde5NuL_h5csMvH6AwkIwDQ-0an7pS64QPbyPujF1z1Hq5zPtm0_FQrFPc5jqgNd1kTb5XDNa7h2$>(2nd 
>>>> point)
>>>>
>>>> Personally, I think nesting in triple terms will not be common, and 
>>>> many levels very, very uncommon.
>>>> But the ability to create triple terms for any triple data does 
>>>> lead to providing for nesting.
>>>>
>>>>     Andy
>>>>
>>>>
>>>>>
>>>>> Thanks,
>>>>> Souri.
>