- From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
- Date: Thu, 15 Oct 2020 08:42:21 -0400
- To: public-rdf-star@w3.org
None of these are RDF triples. They are each shorthand for several RDF triples. The first is _:a _p _:l1 . _:l1 rdf:first _:a . _:l1 rdf:rest _:l2 . _:l2 rdf:first :p . _:l2 rdf:rest rdf:nil . The entire thing is a countably infinite number of triples. I used the wrong term in my original message. I used "element" when I should have used "constituent". RDF* triples have constituents. As sets, RDF and RDF* graphs have elements. peter On 10/15/20 7:29 AM, Jos De Roo wrote: > It was intended as shorthand for > > @prefix : <http://example.org/test# <http://example.org/test#>>. > > _:a :p (_:a :p ()). > _:a :p (_:a :p (_:a :p ())). > _:a :p (_:a :p (_:a :p (_:a :p ()))). > _:a :p (_:a :p (_:a :p (_:a :p (_:a :p ())))). > _:a :p (_:a :p (_:a :p (_:a :p (_:a :p (_:a :p ()))))). > _:a :p (_:a :p (_:a :p (_:a :p (_:a :p (_:a :p (_:a :p ())))))). > _:a :p (_:a :p (_:a :p (_:a :p (_:a :p (_:a :p (_:a :p (_:a :p ()))))))). > ... > > which is perfect RDF > > -- https://josd.github.io/ <http://josd.github.io/> > > > On Thu, Oct 15, 2020 at 1:17 PM Olaf Hartig <olaf.hartig@liu.se > <mailto:olaf.hartig@liu.se>> wrote: > > Jos, this is neither an RDF triple nor an RDF* triple. What is "..."? > > Olaf > > -----Original Message----- > From: Pierre-Antoine Champin <pierre-antoine.champin@ercim.eu > <mailto:pierre-antoine.champin@ercim.eu>> > To: Jos De Roo <josderoo@gmail.com <mailto:josderoo@gmail.com>> > Cc: public-rdf-star@w3.org <mailto:public-rdf-star@w3.org> > Sent: Thu, 15 Oct 2020 12:54 > Subject: Re: how many RDF* triples? > > On 15/10/2020 11:55, Jos De Roo wrote: > > > I was wondering about the difference with > > _:a :p (_:a :p (_:a :p (_:a :p ...))) > > which is an RDF triple with an infinite number of elements > > to me, this is exactly the example that Peter proposed initially -- > unless I am missing something... > > > > > -- https://josd.github.io/ <https://josd.github.io/> > <http://josd.github.io/ <http://josd.github.io/>> > > > > > > On Thu, Oct 15, 2020 at 11:32 AM Pierre-Antoine Champin > > <pierre-antoine.champin@ercim.eu <mailto:pierre-antoine.champin@ercim.eu> > > <mailto:pierre-antoine.champin@ercim.eu > <mailto:pierre-antoine.champin@ercim.eu>>> wrote: > > > > Argh, I realize that I hit "reply" instead of "reply all", when > > answering Peter's original message :-/ > > > > To sum up our exchange: > > > > * the "infinitely nested" triples suggested by Peter should not, in my > > opinion, be allowed, and I don't think Olaf's intention was to > > allow them; > > > > * hence, I reverted the definition of RDF* triples to Olaf's original > > definition (from the paper), which makes this restriction more > > explicit; > > > > * with this restriction, I believe that the set of RDF* triples is > > "only" countably infinite, as any RDF* triple can be serialized into a > > (finite) string. > > > > On 15/10/2020 09:06, Olaf Hartig wrote: > > > Hi Pat, > > > > > > I understand the difference between uncountably infinite sets > > and countably > > > infinite sets, and I see that the set of all possible RDF* > > triples is > > > uncountably infinite. So, in that sense, yes, my comparison to > > literals was > > > imperfect as it was only about infinity without distinguishing > > between the > > > countable and uncountable variant. > > > > > > The main question is whether the uncountable infinity of all > > RDF* triples may > > > cause problems. I don't see how it may cause problems. > > > > > > Thanks, > > > Olaf > > > > > > > > > On onsdag 14 oktober 2020 kl. 16:27:03 CEST Patrick J Hayes wrote: > > >> Hi Olaf > > >> > > >> Not quite the same issue with literals. There are countably > > many literals, > > >> just as there are countably many possible IRIs and countably > > many RDF > > >> graphs. But if Peter is correct, there are uncountably many > > RDF* triples. > > >> An uncountable infinity is a lot more than a countable infinity. > > >> > > >> Pat > > >> > > >>> On Oct 14, 2020, at 8:00 AM, Olaf Hartig <olaf.hartig@liu.se > <mailto:olaf.hartig@liu.se> > > <mailto:olaf.hartig@liu.se <mailto:olaf.hartig@liu.se>>> wrote: > > >>> > > >>> Hi Peter, > > >>> > > >>> Right, there is no bound on the nesting depth. However, I > > don't think that > > >>> this may cause problems. > > >>> > > >>> By the way, the set of literals is infinite as well, so you > > have the same > > >>> issue with RDF triples. > > >>> > > >>> Olaf > > >>> > > >>> On onsdag 14 oktober 2020 kl. 08:46:52 CEST Peter F. > > Patel-Schneider > > > wrote: > > >>>> I was looking at https://w3c.github.io/rdf-star/ > <https://w3c.github.io/rdf-star/> and got to > > wondering how > > >>>> many RDF* triples are there? It appears to me that there are an > > >>>> uncountable number of RDF* triples because there is no axiom of > > >>>> foundation > > >>>> for RDF* triples. > > >>>> > > >>>> So the following is an RDF* triple: > > >>>> > > >>>> _:a :p << _:a :p << _:a :p << _:a :p ... >> >> >> > > >>>> > > >>>> So an RDF* triple could have an infinite number of elements > > and so there > > >>>> is > > >>>> an uncountable number of RDF* triples. > > >>>> > > >>>> Does this cause any problems for RDF*? That I am not sure of. > > >>>> > > >>>> > > >>>> peter > > > > > > > > >
Received on Thursday, 15 October 2020 12:42:38 UTC