From: thomas lörtsch <tl@rat.io>

Date: Tue, 26 Jan 2021 13:44:13 +0100

Cc: public-rdf-star@w3.org

Message-Id: <52DC308B-1FCD-4AD8-927E-ED3D6D499657@rat.io>

To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>

Date: Tue, 26 Jan 2021 13:44:13 +0100

Cc: public-rdf-star@w3.org

Message-Id: <52DC308B-1FCD-4AD8-927E-ED3D6D499657@rat.io>

To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>

> On 25. Jan 2021, at 20:43, Peter F. Patel-Schneider <pfpschneider@gmail.com> wrote: > > Given that :lie is just an RDF node (and an RDFS class) there is nothing here > that dictates any truth value for any node in the graph. So no paradox and > not even a contradiction. > > Even if :lie had its intended meaning (that its instances are false > propositions) there is no contradiction. All that is being stated is that <> > a :lie is not a true proposition and thus cannot be in the graph. There is > nothing here requiring <> a :lie to be a triple in the graph (which would make > it a true proposition), so no contradiction. > > If this was what used to be PG mode Arg… yes, I should have said: <> a :lie {| a :lie |} > then there would be a contradiction, as <> > a :lie would be a triple in the graph. But still no paradox. Okay. > A paradox in a semantic extension of RDF is something that demonstrates that > there can be no models for any RDF graph that is allowable in that extension. > (For example, if "A"^^xsd:int _:b1 _:b2 were a triple in all RDF graphs then > the extension of RDF that recognizes the datatype xsd:int would be > paradoxical.) In early versions of set theory there were lots and lots of > sets that always existed, including a set X which is defined as the set of > things that are not in X. X cannot be in X and X cannot not be in X. As > these are the only two options, a paradox results, but only because this set > always exists. Good. I might try to come up with something that has no model but as of now I understand your response as saying that this attempt is probably futile. Which is a good :) Thanks everybody for the remarks and/or the patience! Thomas > peter > > On 1/25/21 10:38 AM, thomas lörtsch wrote: >> [This question definitely shows a troublesome lack of understanding and research. Feel free to ignore.] >> >> One of the dangers of reification is that it introduces the possibility of paradoxes. The proposed literal-like semantics of RDF* doesn’t seem to give any protection from that. IIUC the following constitutes a paradox: >> >> << <> a :lie >> a :lie . >> >> Or is it only a contradiction? Maybe the monotonic nature of RDF and its lack of all-quantification does make paradoxes impossible? Or at least not harmful? Maybe it would be sufficient to disallow the self-referential <> ? >> >> Is there anything that should be done? That can be done? What are the dangers? >> >> >> Thanks, >> Thomas >> >> >> >Received on Tuesday, 26 January 2021 12:44:36 UTC

*
This archive was generated by hypermail 2.4.0
: Tuesday, 26 January 2021 12:44:37 UTC
*