- From: Anthony Moretti <anthony.moretti@gmail.com>
- Date: Thu, 6 Jan 2022 00:37:19 +1030
- To: thomas lörtsch <tl@rat.io>
- Cc: "Patrick J. Hayes" <phayes@ihmc.org>, Fabio Vitali <fabio.vitali@unibo.it>, Ted Thibodeau Jr <tthibodeau@openlinksw.com>, "public-rdf-star@w3.org" <public-rdf-star@w3.org>
- Message-ID: <CACusdfRno1f7aagtzDTyrhTpzhn4yVLgqGfeo79HU_0OTa=kNg@mail.gmail.com>
Yeah no problem, there are so many emails here. I'll add dates, trying to guess which dates you might mean, but not sure if I've guessed right: *Asserted case:* :Employee38 :jobTitle "Assistant Designer" 2018 2019 { :desk 8 } {| :statedBy :Employee22, :stated 2022 |} . Expands to: :Employee38 :jobTitle "Assistant Designer" 2018 2019 . { :Employee38 :jobTitle "Assistant Designer" 2018 2019 } :desk 8 . << :Employee38 :jobTitle "Assistant Designer" 2018 2019 >> :statedBy :Employee22 . << :Employee38 :jobTitle "Assistant Designer" 2018 2019 >> :stated 2022 . << { :Employee38 :jobTitle "Assistant Designer" 2018 2019 } :desk 8 >> :statedBy :Employee22 . << { :Employee38 :jobTitle "Assistant Designer" 2018 2019 } :desk 8 >> :stated 2022 . *Unasserted case:* << :Employee38 :jobTitle "Assistant Designer" 2018 2019 { :desk 8 } >> {| :statedBy :Employee22, :stated 2022 |} . Expands to: << :Employee38 :jobTitle "Assistant Designer" 2018 2019 >> :statedBy :Employee22 . << :Employee38 :jobTitle "Assistant Designer" 2018 2019 >> :stated 2022 . << { :Employee38 :jobTitle "Assistant Designer" 2018 2019 } :desk 8 >> :statedBy :Employee22 . << { :Employee38 :jobTitle "Assistant Designer" 2018 2019 } :desk 8 >> :stated 2022 . Is that what you mean? Thanks for looking this over by the way. Regards Anthony On Thu, Jan 6, 2022 at 12:21 AM thomas lörtsch <tl@rat.io> wrote: > > > > Am 05.01.2022 um 14:45 schrieb Anthony Moretti < > anthony.moretti@gmail.com>: > > > > Actually, just a day ago I sent an example like that, I modified example > 1 from the CG report to make it a 3-ary relationship. I'll paste it here > for you: > > > > Asserted case: > > :Employee38 :jobTitle "Assistant Designer" > > { :desk 8 } > > {| :accordingTo :Employee22 |} . > > > > Expands to: > > > > :Employee38 :jobTitle "Assistant Designer" . > > { :Employee38 :jobTitle "Assistant Designer" } :desk 8 . > > << :Employee38 :jobTitle "Assistant Designer" >> :accordingTo > :Employee22 . > > << { :Employee38 :jobTitle "Assistant Designer" } :desk 8 >> > :accordingTo :Employee22 . > > > > Unasserted case: > > << > > :Employee38 :jobTitle "Assistant Designer" > > { :desk 8 } > > >> > > {| :accordingTo :Employee22 |} . > > > > Expands to: > > > > << :Employee38 :jobTitle "Assistant Designer" >> :accordingTo > :Employee22 . > > << { :Employee38 :jobTitle "Assistant Designer" } :desk 8 >> > :accordingTo :Employee22 . > > > > The different delimiters "{ }" and "{| |}" enable you to leave the first > section blank and still recognize the second section as metadata rather > than data, for example: > > > > :Employee38 :jobTitle "Assistant Designer" > > {| :accordingTo :Employee22 |} . > > > > The above is the same as the current annotation syntax in the report > actually. > > > > It seems to work but yeah I could be missing something, > > I’m missing the dates in this example so I don’t know how this response > relates to your last response (to which I replied that I do indeed > disagree). I also don’t see how it relates to my initial post on this > thread about multisets so please forgive me if I don’t give all of your > posts my full attention. > > Thomas > > > > > if you have examples of how it doesn't work please send them and I'll > take a look. The more critiquing the better IMO. > > > > Regards > > Anthony > > > > On Wed, Jan 5, 2022 at 11:03 PM thomas lörtsch <tl@rat.io> wrote: > > > > > > > Am 05.01.2022 um 00:40 schrieb Anthony Moretti < > anthony.moretti@gmail.com>: > > > > > > Hi Thomas > > > > > > A side note about what a statement states and what it doesn’t state > (unrelated to what I said above, but as the topic came up in this thread > recently): the much discussed example > > > <<:Burton :marriedTo :Taylor>> :start 1963; :end 1974 . > > > can be read as > > > "Let’s assume a statement claiming a marriage relation between > Burton and Taylor. > > > That marriage relation starts in 1963 and ends in 1974." > > > That’s okay (ignoring for a moment the httpRange-14 issue, that start > and end dates could also refer to the statement itself). The second > sentence adds detail about which the first sentence makes no claim. It is > important that properties are defined in a way that they welcome such > additional information, not prohibit it. The design principle that no > statement is allowed to alter the truth of another one OTOH also requires > that no statement is allowed to forbid the addition of further detail by > other statements. If we can’t rely on that we can forget about weaving a > semantic web from disparate sources. > > > > > > I'd say most of us on this thread agree by now that that statement is > improperly structured. Optional time and space positions, and other fixes I > suggested in my two previous messages, seem to solve the problem entirely > though. I guess you disagree? > > > > Yes I do disagree. Just beacuse this example uses dates doesn’t mean > that dates are the only possible application of statement annotation. Your > approach doesn’t scale to other dimenions, not even to the also very > popular example of provenance information. > > > > Thomas > > > > > > > Asserted case: > > > :Burton :marriedTo :Taylor 1964 1974 > > > {| > > > :stated 2022 > > > |} > > > > > > Expands to: > > > > > > :Burton :marriedTo :Taylor 1964 1974 > > > << :Burton :marriedTo :Taylor 1964 1974 >> :stated 2022 > > > > > > Unasserted case: > > > << :Burton :marriedTo :Taylor 1964 1974 >> > > > {| > > > :stated 2022 > > > |} > > > > > > Expands to: > > > > > > << :Burton :marriedTo :Taylor 1964 1974 >> :stated 2022 > > > > > > Regards > > > Anthony > > > > > > On Wed, Jan 5, 2022 at 12:55 AM thomas lörtsch <tl@rat.io> wrote: > > > > > > > > > > Am 04.01.2022 um 08:46 schrieb Patrick J. Hayes <phayes@ihmc.org>: > > > > > > > > I had vowed to drop out of this discussion, but now I understand > what you are actually saying (sorry it took so long), I feel I need to > respond to it. I see that your interpretation of RDF-star is what we might > call completely opaque. The 'inner' triple is quoted, treated simply as a > piece of syntax. The semantics – the meaning – of the annotation triple > bears no relation to any meaning that the inner triple might have (when > treated as RDF): it is a purely syntactic payload. The annotation – outer – > triples have an uninterpreted triple as their subject. > > > > > > > > I will confess that I simply did not believe, until now, that anyone > could possibly be advocating this idea; but OK, let me just point out some > of the problems it introduces, then I will go back to quiet retirement. > > > > > > RDF-star quoted triples are per the proposed semantics defined as > referentially opaque (modulo some tricks with bnodes). Isn’t this quite > similar to the semantics for named graphs that Carroll et al proposed in > 2004? Of course quoted triples are also types whereas named graphs per that > proposal are occurrences but that doesn’t seem to be a topic in this > discussion IIUC. > > > > > > > First, I note that this has absolutely nothing to do, now, with our > earlier talk of n-ary relations and how to encode them in a binary > framework (which is where I came in). There are no n-ary relations in this > opaque framework, not even implicitly. That entire discussion was > irrelevant to a notation with this interpretation. > > > > > > The RDF-star CG report is not really clear about this. Whenever things > get technical its advocates resort to the position that the quoted triple > is purely syntactic and anything else is not yet specified - see for > example the informal :occurrenceOf property. Whenever the utility of such > an instrument and its applicability for expressed needs like more concise > reification or property graph style modelling is questioned, the answer is > - depending on who is asking - that of course this is possible too, just > not yet fully specified, or that it is "a can of worms" better to be stayed > away from. > > > > > > I have to confess that I was so occupied with occurrences that I > didn’t see the problem that you point out w.r.t. to the marriage example. > The marriage example is indeed about a type - the triple described by the > quoted triple <<:Burton :marriedTo :Taylor>>, meaning the same everywhere > itis stated - and annotations to it. I think the gist of this specific > aspect is an httpRange-14 problem: do we interpret > > > <<:Burton :marriedTo :Taylor>> > > > as referring to a triple of that type (albeit modulo co-denotation) or > to the syntactic string itself (modulo blank nodes, but that’s another > issue). Both interpretations are reasonably well possible and as I said > above they are both supported, albeit in different ways, by the CG.(*) > > > > > > Just as with any other identifier on the semantic web it is quite easy > to come up with intuitive examples of how a statement talks either about > the document itself or what it documents. It is mostly the properties that > disambiguate the referent to the human reader, and applications do the same > implicitly for poor machines. That’s why the semantic web is working > despite this fundamental ambiguity in identification semantics. > > > This disambiguation however gets increasingly complex with quoted > triples as it will have to take the property inside the quote into account > as well: a start and end date on a ex:marriedTo relation makes some sense, > not so much on a quoted triple itself (but it might describe when a triple > was added/removed from some source). An ex:occursIn property doesn’t make > much sense on a marriage relation itself, therefor it probably refers to > the syntactic triple (however there might be a vocabulary using some > :occursIn property to record where the married couple lived, where the > wedding took place etc). When the context is application specific > machinistic ongoings like versioning and explainable AI the httpRange-14 > problem is not much of an issue - but only then, I assume - as the > application context is specifically targeting the triples as syntax, and > not much interested in what they mean (actually rather actively trying to > ignore their meaning). > > > > > > By and large one will be excused to think that the quoted triple > refers to an actual statement of the same form, just without the enclosing > chevrons (and no matter if it actually has been asserted or not) as this > assumption is implicit even in versioning and explainable AI use cases that > motivate the proposed semantics. There is an assumed connection between the > quoted triple and the triple it quotes, despite the fact that the quoted > triple is just a syntactic representation of the real thing. Well, I agree > that this is muddled and brittle and skewed in several ways - I was never a > fan, I’m just the messenger here. But I also think that the httpRange-14 > problem is still by and large unsolved and requires a solution on its own > and RDF-star is not to be blamed for it. But contrary to some popular > believes RDF-star even in its pure, type-centric incarnation falls victim > to that problem just like any other identifying something in RDF - thanks > for pointing that out! > > > > > > > > > A side note about what a statement states and what it doesn’t state > (unrelated to what I said above, but as the topic came up in this thread > recently): the much discussed example > > > <<:Burton :marriedTo :Taylor>> :start 1963; :end 1974 . > > > can be read as > > > "Let’s assume a statement claiming a marriage relation between > Burton and Taylor. > > > That marriage relation starts in 1963 and ends in 1974." > > > That’s okay (ignoring for a moment the httpRange-14 issue, that start > and end dates could also refer to the statement itself). The second > sentence adds detail about which the first sentence makes no claim. It is > important that properties are defined in a way that they welcome such > additional information, not prohibit it. The design principle that no > statement is allowed to alter the truth of another one OTOH also requires > that no statement is allowed to forbid the addition of further detail by > other statements. If we can’t rely on that we can forget about weaving a > semantic web from disparate sources. > > > > > > > > > Best, > > > Thomas > > > > > > > > > (*) In case the quoted triple refers only to the type as syntactic > string (and it is very important to the proponents of this semantics that > it refers to the type, not some occurrence) it might seem that there is > very little that can sensibly be said about it, like > > > <<:Burton :marriedTo :Taylor>> :length 26 . // if I counted > correctly > > > Especially the much touted application in explainable AI or versioning > might be considered a mistake as it records occurrences of some (type of) > triple. Yet, the following example: > > > <<:Burton :marriedTo :Taylor>> :occursIn :ETLstep_25 . > > > describes the occurrence of said type in ETL step 25 just fine. > > > To record further detail about such, possibly multiple occurrences > would however require minting identifiers for them (and we're back at > multisets which, as the title of this thread still suggests, are lurking > just everywhere ;-) > > > > > > > > > > > > > > > >> On Jan 3, 2022, at 1:50 PM, Fabio Vitali <fabio.vitali@unibo.it> > wrote: > > > >> > > > >> Dear Pat: > > > >> > > > >>>> I also think that the gist of our disagreements is in expecting > that all our triples represent "facts" about "reality" (independently of > who asserts them) rather than, say, representing "statements" (asserted by > someone) that can be expressed either "absolutely" or "subject to boundary > conditions". > > > >>> > > > >>> No, wait. We need to agree on terminology. > > > >>> > > > >>> Suppose I say to someone, "Felix is hungry." Then I have > /uttered/ a sentence with three words in it, a physical token of a > syntactic entity. By making that utterance, I have /asserted/ a proposition > which we could represent as 'The cat named 'Felix' at ///pure.hung.skips is > hungry at time 19:45 PST on 1.1.2022' where the implicit indexicals have > all been filled in with objective time/space coordinate references. > > > >>> > > > >>> Now, the meaning of the utterance was contextual, ie indexical: it > could have had a different meaning if uttered by someone else, somewhere > else, at a different time. But the (proposition expressed by) the second > sentence is not contextual in this way. Its truth does not depend on who > asserts it, or where or when it is asserted. It is simply true; and if it > had not been true, it would have been simply false. And this is a standard > and general-purpose way of getting to sentences which have a > straightforward relationship to truth. It is used (pwerhpas implicitly) by > virtually all data formats, and has been used since bookkeeping was > invented probably in the ferrtile crescent. Anyone who stamps a date onto a > document before filing it is using this device. > > > >>> > > > >>> Propositions are either true or false. By asserting a proposition, > I am claiming it to be true. Not, note, true in a context or true at a > time, becasuse we have included all that indexical variation into the > proposition itself; but just plain true. The "boundary conditionss", by > being mentioned explicitly, have become part of the proposition whose > truthvalue is being claimed by the assertion. > > > >>> > > > >>> Now, this all maps into the semantic web world of RDF, OWL, etc. > as follows: the RDF graph is a sentence which is REQUIRED (by the normative > semantics) to be true or false, ie to have.a simple truthvalue. Publishing > some RDF is asserting it to be true. And all of that is part of the > definition of RDF, so if y'all want to use it in any other way, well, it's > a free country, but just be aware you are mis-using it. > > > >> > > > >> Ok. let's try again dotting all i's and crossing all t's. > > > >> > > > >> Entity A publishes an RDF dataset containing several triples of the > form (s_i p_i o_i). Each of them is asserted, i.e. assumed to represent a > fact from the point of view of A. They are either "simply true" or at least > "simply true for A". > > > > > > > > A is asserting them, ie claiming them to be true. The claim belongs > to A; the truth that is claimed belongs to the triples. > > > > > > > >> > > > >> Now. With rdf-star, a few of these triples may have a form such as > either the subject or the object are RDF* quoted triples << s_j p_j o_j >> > : > > > >> > > > >> << s_j p_j o_j >> p_i o_i . > > > >> > > > >> Quoted triples are not asserted, we agree on this, and they are > neither "simply true" nor "simply true for A". At the same time, they are > not simply false nor simply false for A. Their truth value is unspecified. > We do NOT know if (s_j p_j o_j) is true or false. > > > > > > > > Just say: they are not being asserted by A (at least not here). The > rest of the verbiage is unnecessary and confusing. > > > > > > > >> A great deal of effort was created by this community to ensure that > the semantics of RDF was not broken even if we added triples that have no > truth value, provided we quote them and place them inside a contextualizing > triple, which on the contrary IS asserted. > > > >> > > > > > > > > OK, I follow that now. (I would say, though, that if that is all you > wanted to do, it isn't very difficult. Just put RDF triples as entities > into an RDF interpretation, and require the quoting syntax to have the > obvious meaning, ie " 'foodle' " denotes 'foodle'. It is two lines added to > the RDF spec, and is indeed a legal RDF semantic extension.) > > > > > > > > (BTW, an aside. The first RDF WG could have defined the meaning of > RDF reification in this kind of way, ie as quotation. But we decided it > would be useless, and in any case would not carry what seemed to be the > intent of reification (which had been defined by an earlier group and we > were chartered to not alter). Which is why reification is not opaque.) > > > > > > > >> Thus said: > > > >> > > > >>>> I guess I have a fundamentally nominalistic perspective in which > the temporal constraints in > > > >>>> > > > >>>>> << :RichardBurton :marriedTo :LizTaylor >> > > > >>>>> :startDate "1963"^^xsd:Year; > > > >>>>> :endDate "1974"^^xsd:Year; > > > >>>> > > > >>>> are NOT about the reality (i.e., the marriage between Rick and > Liz), but about the knowledge context that makes the statement actually > asserted. They are about what we KNOW (and how we decide to represent it), > and not about what IS. > > > >>> > > > >>> Well, I can argue against the utility and indeed accuracy of such > a view, and will do so briefly below, but more to the point is that RDF > requires that an asserted triple is asserted without a context. Put another > way, the truth of the RDF triple > > > >>> > > > >>> :RichardBurton :marriedTo :LizTaylor . > > > >>> > > > >>> in any RDF interpretation does not, and normatively cannot, depend > on any assertions made /about/ that triple. So once asserted, it is > asserted without any surrounding context or qualification. Which means that > your interpretation is inconsistent with the (sorry to repeat) normative > semantics of RDF. > > > >> > > > >> The triple :RichardBurton :marriedTo :LizTaylor was never present > in the RDF dataset. It is nowhere to be seen. The only triples that WERE > asserted, i.e., provided with a truth value, are: > > > >> > > > >> << :RichardBurton :marriedTo :LizTaylor >> :startDate > "1963"^^xsd:Year; > > > >> << :RichardBurton :marriedTo :LizTaylor >> :endDate > "1974"^^xsd:Year; > > > >> > > > >> I asserted them, and I expect them to be understood as "simply true > for me". I am not breaking any RDF semantics so far. > > > > > > > > Indeed, you are not. But you are also not saying anything about > Richard Burton, Liz Taylor, or the relation marriedTo. So what does > startDate mean here? The triples seem to say that these dates are the start > and end dates of a triple, but what does THAT mean? Why would a triple have > a date? > > > > > > > > … > > > > > > > >> > > > >>> But to return to your 'nominalist' (?) claim. You are saying that > (for example) > > > >>> > > > >>> :startDate "1963"^^xsd:Year; > > > >>> > > > >>> is not actually a statement about the date of Dick & Liz's > marriage, but rather is about what "we know". > > > >> > > > >> No. I am saying that it provides a temporal condition on the quoted > triple << :RichardBurton :marriedTo :LizTaylor >> > > > > > > > > But what does THAT mean? How can an RDF triple have a 'temporal > condition'? It is hard to see how thas can mean anything other than a > condition on its being true. > > > > > > > > (This is where the rubber meets the road for a semantic account, by > the way, because if you give that idea of "temporal (and presumably other) > condition" flesh, you will I predict have to break the clean picture of > this being a form of opaque quotation.)(See below.) > > > >> > > > >> I am on purpose moving away from describing the reality (or even > the reality as the author of the dataset sees it) and start adding > conditions on what is said about reality. They may (and usually have) a > connection to the reality (or to the reality as me as the author see it), > but, again, this is an added bonus, not a requirement. > > > > > > > > But when they do, do you want that connection to be semantically > significant? Will the meaning of the RDFstar nested triple ever have ANY > connection to the meaning of the inner, quoted, triple? If so, this is not > just quotation. > > > > > > > >> > > > >>> Really? About what WHO knows? (To speak of knowledge without a > knower is nonsensical.) But in any case, surely this is just wrong. It is a > piece of information about the date of a marriage, not about knowledge at > all. Of course one could say something like that this assertion represents > part of what is 'generally known' about the marriage, but still it is the > sentence that is generally known, and what the sentence refers to is a > marriage date, not a belief about a date. > > > >> > > > >> By interpreting :startDate "1963"^^xsd:Year as an attribute of a > marriage, you are still trying to force a Marriage entity inside a (quoted) > triple where no Marriage entities have been specified. > > > > > > > > I think I am only stating the obvious intended meaning of the > RDFstar here. Other readers of this thread (if there are any), would you > interpret this as making an assertion about the date of a marriage? > > > > > > > >> > > > >> I am not saying that using Marriage entities is wrong in general: I > am saying that within the quoted triple << :RichardBurton :marriedTo > :LizTaylor >> there is the predicate :marriedTo, not a Marriage entity. > > > > > > > > There is neither of them. There is only a URI ':marriedTo', which is > a character string. Triples contain syntax, not relations. > > > > > > > >> If you want to use a Marriage entity, you have to get rid of the > :marriedTo predicate and use a whole bunch of new predicates (:groom, > :bride, etc.) and apply them to a newly created entity of type Marriage. > You are fundamentally restructuring and revolutionising the ontology adding > many new predicates and entities and throwing away some old ones. Probably, > conceptually, the best approach (but is HAS limitations), but at the same > time this is a fairly invasive procedure, not always possible. > > > >> > > > >>>> In other words, the propositions we are considering should not be > viewed as absolutely true or false (or, as you say, simply true or false), > but are true when a given state of affairs is obtained. > > > >>> > > > >>> No, that is not what this says. When Lindström says "make some > proposition about the actual world true" he is saying the proposition is > ABOUT the state of affairs (which is a real aspect of the actual world), > and it IS true – simply true – just when the world does indeed contain (or > maybe /exemplify/ or some such locution: philosophers vary here) that state > of affairs. Saying that a proposition is simply true does not imply that > the world it describes must be simple. So for example, the proposition that > Liz and Richard were married from 1963 to 1974 is true – simply true – > because the state of affairs it describes is actual, in the actual world. > (If it were "true of" a state of affairs, ie if it needed something extra > to make it have a simple truth value, then it would be a predicate, not a > proposition.) > > > >> > > > >> Please. I am not objecting to whether or not "the proposition that > Liz and Richard were married from 1963 to 1974 is true – simply true". Of > course, I accept that it is true. > > > > > > > > OK, though you did SEEM to argue against it fairly strongly. No > doubt I misunderstood you. > > > > > > > >> But this is NOT what these triples are saying: > > > >> > > > >> << :RichardBurton :marriedTo :LizTaylor >> :startDate > "1963"^^xsd:Year; > > > >> << :RichardBurton :marriedTo :LizTaylor >> :endDate > "1974"^^xsd:Year; > > > >> > > > >> These triples are not about a Marriage entity, but about the quoted > triple << :RichardBurton :marriedTo :LizTaylor >> . > > > > > > > > OK, they are about a triple. Got that. But… > > > > > > > >> They represent an extremely simple way to add temporal constraints > to knowledge, because they do not annotate the Marriage, but the quoted > triple. > > > > > > > > …then they DONT add temporal constriants /to knowledge/. They add > temporal constriants to syntax, to triples (whatever that means). Those > annotated triples are no longer data when they are merely quoted: they have > been stripped of content. > > > > > > > >> > > > >>>> Facts about the reality are either (simply) true or (simply) > false. On the contrary, conditions about a quoted triple allow us to either > ASSERT or NOT ASSERT the triple itself. > > > >>> > > > >>> You assert it by publishing it as RDF data. And you 'not assert' > it by not publishing it. That is wired into the semantics of RDF. > > > >> > > > >> One of the most interesting contribution of RDF* is the ability of > publishing triples without asserting them, as "quoted triples", and without > breaking the usual RDF semantics. > > > >> > > > >> We are just exploring what we can do with non-asserted triples, but > talking and constraining quoted triples is VERY interesting from my point > of view, because it allows us to discuss about facts that are locally true, > or temporally constrained, or conjectural, or hypothetical, or even plainly > and laughably false, WITHOUT asserting them and without breaking the usual > RDF semantics. > > > > > > > > Sure, I have no problems with most of this, as long as we are > talking strictly about the triples. But some of this – notably, "temporally > constrianed" – is not about the triples, but (in spite of your > protestations to the contrary) about what the triples MEAN. And that does > break the RDF semantics. > > > > > > > >> > > > >>>> The quoted triple is neither true nor false, it is provided for > contemplation, so to speak, and becomes asserted under some conditions. > > > >>> > > > >>> No. We can make assertions about this notorious marriage now, in > 2022. We do not (cannot) travel back in time to 1963 in order to make > assertions about what happened then. So these dates are not the dates of > assertions. (Did you read what I wrote earlier about valid time vs. > transaction time?) > > > >> > > > >> Now you are assuming that :startDate "1963"^^xsd:Year is the date > of the assertion. It is not. I guess you are misreading the name of the > :startDate predicate, so I'll use another one. > > > >> > > > >> << :RichardBurton :marriedTo :LizTaylor >> :atLeastSince > "1963"^^xsd:Year; > > > >> << :RichardBurton :marriedTo :LizTaylor >> :atMostUpTo > "1974"^^xsd:Year; > > > >> > > > >> Any better? I am saying that 1963 is the safest early date where we > can expect the quoted triple << :RichardBurton :marriedTo :LizTaylor >> > to be assertable. > > > > > > > > AssertABLE but not assertED. This is a very delicate distinction to > place so much reliance on. What does 'assertable' mean? As a matter of > fact, it wasn't assertible in 1963 because RDF hadn't been invented in > 1963. Seriously, you have to say what this locution "assertable in X" > means. No matter how much you wriggle, I will claim, and I bet 99% readers > of that RDFstar will agree, that you are talking about when the inner > triple was TRUE. And then you run right into the fact that the RDF > semantics doesn't provide for a tensed truth-at-one-time-but > maybe-not-another. > > > > > > > >> Note that I am NOT asserting it, just providing temporal boundary > conditions for its assertability. Indeed, the triple :RichardBurton > :marriedTo :LizTaylor is NOT true > > > > > > > > You mean, not true NOW, I presume. But RDF has no notion of "now". > It is not a tensed language. > > > > > > > >> , and therefore I do not feel like asserting it. > > > >> > > > >> In fact, and this is what makes RDF* interesting, we can work with > temporal conditions around quoted triples without feeling any pressure to > assert the triples and without breaking the semantics of RDF. > > > >> > > > >>>> These are the conditions that obtain the corresponding state of > affairs. Under this conceptual frame, the idea of a true triple is foreign > and frankly irrelevant: they are are not true or false (this pertains to > reality, or possibly to knowledge), but asserted or non-asserted (this > pertains to knowledge representation). > > > >>> > > > >>> Well (1) this conceptual frame is incompatible with RDF, but also > (2) as stated, it is incoherent, or at best muddled. You should try making > it formal, and you will soon discover the problems. You will need some > variation on the semantics of context logic, by the way. > > > >> > > > >> No no. I am saying, loudly and clearly, that I am NOT making > anything incompatible with RDF, and that I am using the plain and old RDF > semantics, and that if you see contradictions is only because you keep on > seeing (made up) entities that are not there in the first place, such as > Marriages, and assertions that are not there in the first place, such as > :RichardBurton :marriedTo :LizTaylor. > > > >> > > > >> > > > >> > > > >>> > > > >>>> Why is this interesting? > > > >>>> > > > >>>> 1) because they do not require you to first adopt new entities > such as states or events. You can keep on using simple triples representing > trivial binary relationships. > > > >>>> > > > >>>>> I do not regard events as PSEUDO entities, myself. In fact, the > world is pretty much comprised of events, in a suitably broad sense. > > > >>>> > > > >>>> Yes, you are probably right. Still, not everybody is using > events, not everybody has used events in existing datasets. Should we > replace all simple binary relationships with TSD n-ary relationships based > on events? More correct, probably. But... > > > >>>> > > > >>>> On the other hand, quoting an existing triple is always possible, > regardless of the type of conceptual representation that was adopted. > > > >>> > > > >>> But changing its truthvalue by adding meta-descriptions is not > possible. And claiming that it never had a truthvalue until the metadata > was added is even more peculiar. So this is not just RDF-as-usual you are > talking about. > > > >> > > > >> I am not changing its truthvalue by adding meta-descriptions. > > > >> > > > >> I am not claiming that it never had a truthvalue until the metadata > was added. > > > > > > > > So what would it mean to publish that inner triple named, as it > were, without any annotations? (Because people will do this, whether you > like it or not.) Would it mean that the triple is true now? That violates > the RDF semantics, which has no notion of 'now'. Or does it mean there > EXISTS a time (unspecified) when it is true? OK, make that existential > explicit in RDF, it is a bnode. Now relate that bnode to the other things > mentioned in the triple... I am sure you can see where this is going to end > up. > > > > > > > >> I am simply saying that through RDF* we can discuss about quoted > triples without ever caring about their truthvalue, whether they are simply > true, or temporally bound, or hypothetical, or absurd. Their truthvalue is > NOT RELEVANT ANYMORE, and we still are not breaking the usual RDF > semantics. > > > > > > > > This would be fine if it were true, but I simply don't believe it, > and its not consistent with your claim that RDFstar content is 'data'. Does > > > > > > > > << :RichardBurton :marriedTo :LizTaylor >> :startDate > "1963"^^xsd:Year; > > > > > > > > say anything about Elizabeth Taylor, or not? If not, it is not data > in any meaningful sense. If yes, then this is not simply quotation of a > triple. > > > > > > > >>>> Right. Good. There are totally expressive representations of > reality. I am fine with that and I trust you that it could be done and it > has been done. But around here there are a lot of much simpler knowledge > representations that haven't gone that far in the correctness of the > underlying ontology. They are not wrong per se, but just a bit too simple > for these fine points. Quoting is an approach that allows us to represent > TSD representations without rewriting them all. > > > >>> > > > >>> But it does not, or at least not without a complete overhaul and > rewrite of the RDF semantics, which would likely change the intended > meaning of all those simple triples. And has not been done, in any case. > > > >> > > > >> No. You would be right if I was trying to consider quoted triples > as plain RDF triples, which I am not doing. > > > > > > > > ? I thought that was exactly what you were insisting that you were > doing. This: > > > > > > > > :RichardBurton :marriedTo :LizTaylor > > > > > > > > is an RDF triple. Really, it is. It conforms to the RDF syntax > rules, so… > > > > > > > > > > > >> > > > >>>>>>> << :monaLisa dc:creator :leonardo >> > > > >>>>>>> :startDate "1516"^^xsd:Year. > > > >>>>>> > > > >>>>>> The temporal constraint is about the truth of the triple, and > not about a creationEvent which I did not use, and is therefore true. > > > >>>>>> > > > >>>>> … is it? What does :startDate mean? Suppose we discover that > Leonardo actually painted it in 1513. Surely, in that case, this assertion > about start date would be /wrong/. But this discovery should be consistent > with the facts we currently have (and which your RDF should express). > > > >>>> > > > >>>> The quoting triple does not talk about :monaLisa, and does NOT > mean that :monaLisa was created in 1516. It talks about the quoted triple, > and states this triple is asserted in all states of affairs after 1516. > Before that time, the statement is unasserted, not false: before 1516, we > have no information about its assertedness. This is correct. > > > >>> > > > >>> But that is not how 'startDate' is interpreted in other cases, > like the marriage. And I suggest it is a very bad idea to impose this > open-ended interpretation as a norm. How are you going to represent that > actual date, if this is ever determined? > > > >> > > > >> You are right, maybe the choice of ":startDate" can lead humans to > misinterpret what is being said, I'll use :atLeastSince from now on. > > > >> > > > >>>> 4) because conditions aggregate and do not generate > inconsistencies. They may generate unobtainable states of affairs, but not > logical inconsistencies. For instance, these quoted triples are all > correct: > > > >>>> > > > >>>>> << :monaLisa dc:creator :leonardo >> > > > >>>>> :startDate "1516"^^xsd:Year. > > > >>>>> << :monaLisa dc:creator :leonardo >> > > > >>>>> :startDate "1715"^^xsd:Year. > > > >>>>> << :monaLisa dc:creator :leonardo >> > > > >>>>> :startDate "2021"^^xsd:Year. > > > >>>> > > > >>>> These are all legitimate statements, compatible with each other > and do not generate any inconsistency. > > > >>> > > > >>> Not in your odd interpretation, no. But nobody else is using that > interpretation. it seems to me that they /should/ be mutually inconsistent. > This is a bug, not a feature. I dread to think what kind of nonsensical > conclusions could be drawn from that last one, eg that Leonardo was 569 > years old in 2021. > > > >> > > > >> These triple are not about Leonardo or about Mona Lisa, they are > about the quoted triple << :monaLisa dc:creator :leonardo >> which (I am > asserting) was assertable in 1516, in 1715 and even in 2021. > > > > > > > > Is there any time when it would not be assertable? If not, it seems > rather vacuous to use a date at all. > > > > > > > > OK, your strange ontology of time relations is really a side topic. > I think it is barmy, myself, but whatever. Not relevant to the main topic. > > > > > > > >> The age of Leonardo is not even hinted at, here. > > > > > > > > Well, it is surely being HINTED at. > > > > > > > >> > > > >> To clarify it better, let me try again with the newly named > :atLeastSince predicate: > > > >> > > > >>>>> << :monaLisa dc:creator :leonardo >> > > > >>>>> :atLeastSince "1516"^^xsd:Year. > > > >>>>> << :monaLisa dc:creator :leonardo >> > > > >>>>> :atLeastSince "1715"^^xsd:Year. > > > >>>>> << :monaLisa dc:creator :leonardo >> > > > >>>>> :atLeastSince "2021"^^xsd:Year. > > > >> > > > >> > > > >> > > > >> These are not assertions about a Creation event for a painting, but > assertions about temporal conditions on a (quoted) triple. > > > > > > > > And what does THAT mean? Apparently, it implies nothing about the > entities mentioned in the triple. And I have no idea what it means to say > say that triple has a temporal constraint on it. (Not, of course, on its > truth, right?) > > > > > > > >> The "at least" bit emphasises that these are minimal temporal > requirements, not precise boundaries. > > > >> > > > >> Now let's try a simple SPARQL+ query: "please tell me what pictures > by Leonardo existed in May 1517" (Leonardo moving to France). I separate > them in three sets: those that do not have a :atMostUpTo annotation, those > that do not have a :atLeastSince annotation, and those that have both; > these sets includes all cases. > > > >> > > > >> SELECT DISTINCT ?painting WHERE { > > > >> { > > > >> << ?painting dc:creator :leonardo >> > > > >> :atLeastFrom ?date1 . > > > >> :atMostUpTo ?date2 . > > > >> FILTER ( > > > >> ?date1 <= "1517-05-01"^^xsd:dateTime && > > > >> ?date2 >= "1517-05-31"^^xsd:dateTime > > > >> ) > > > >> } UNION { > > > >> << ?painting dc:creator :leonardo >> > > > >> :atLeastSince ?date . > > > >> FILTER (?date >= "1517-05-01"^^xsd:dateTime ) > > > >> } UNION { > > > >> << ?painting dc:creator :leonardo >> > > > >> :atMostUpTo ?date . > > > >> FILTER (?date <= "1517-05-31"^^xsd:dateTime ) > > > >> } > > > >> } > > > >> > > > >> This query works with SPARQL*, it is compatible with the RDF > semantics, and, crucially, it returns the right results. Of course I know I > am not querying Creation events, but annotations about simple (and > apparently irrelevant) triples. Still it does work and it is correct and > it is (I believe) much simpler to devise and write than a query using > creation and destruction events, most of which we have no data about. > > > > > > > > Sure, but this is easy. Pretty much any syntactic pattern which > makes a recognizable connection between the items you want will return the > results when you query it with a matching pattern. Provided of course that > you get the pattern /exactly/ right. > > > > > > > >>>> 5) because you can represent in a much simpler way competing and > incompatible statements. For instance, as we discussed, Mona Lisa was > certainly painted before 1516, but scholars discuss about exactly when: the > Louvre Museum believes it was painted in 1506, Alessandro Vezzosi after > 1513. If we rely on events, this becomes rather complicated: > > > >>>> > > > >>>>> :c1 a :creationEvent; > > > >>>>> :work :monaLisa; > > > >>>>> :creator :leonardo; > > > >>>>> :date "1506"^^xsd:Year; > > > >>>>> :source :louvre. > > > >>>>> > > > >>>>> :c2 a :creationEvent; > > > >>>>> :work :monaLisa; > > > >>>>> :creator :leonardo; > > > >>>>> :date "1513"^^xsd:Year; > > > >>>>> :source :vezzosi. > > > >>>> > > > >>>> Both creationEvents exist and refer to the same entities. Only > the date and the source differ. How can we assert a preference? That is not > clear to me. How do we state that the painting surely existed in 1516, a > notion that is implicit but never specified because there is no > creationEvent listed for 1516? That is not clear to me. > > > >>> > > > >>> I would prefer to say that there is one event, but two opinions as > to its starting date. And to say that, we need a (single) name to the > event. There is no way to directly express such a difference of opinion in > any single RDF graph, because it is a genuine divergence about the facts, > and RDF can only describe one world at a time, so to speak. I would use a > construct like an RDF dataset to encode such divergences of opinion, with > separate graphs for each source. > > > >> > > > >> You say: "There is no way to directly express such a difference of > opinion in any single RDF graph.". > > > >> > > > >> Yes, there is! There is NOW (using RDF-star, I mean). > > > >> > > > >> That's my whole reason for using RDF-star (and my proposal, > conjectures): to express differences of opinion. This is what makes them > valuable! Thus, > > > >> > > > >> << > > > >> << :monaLisa dc:creator :leonardo >> > > > >> :startDate "1506"^^xsd:Year > > > >>>> :accordingTo :louvre. > > > >> > > > >> << > > > >> << :monaLisa dc:creator :leonardo >> > > > >> :startDate "1513"^^xsd:Year > > > >>>> :accordingTo :vezzosi. > > > >> > > > >> expresses two points of view that are incompatible with each other. > Yet the resulting dataset is not inconsistent, not wrong, and fully within > the accepted RDF semantics. That is what makes rdf-star precious. > > > > > > > > As I undertand this – and apologies if I have this wrong – there are > two RDFstar triples in each assertion here, each having the (quoted) > triple << :monaLisa dc:creator :leonardo >> as subject. But then the > final triple in each pair seems to be attributing this triple to two > different sources, not the other annotation triple (which refers to a > date). Which seems wrong. > > > > > > > > (Or should I read this as a three-deep nesting of triples, where the > startDate triples have that as subject, and are then quoted again and are > then the subject of the next triple, so that the quotations are nested > inside one another? That makes more sense, but nested quotation amplifies > my concerns about quoted syntax not being real data.) > > > > > > > >>>> > > > >>>> By using RDF* and truth conditions, these assertions becomes easy > and explicit. > > > >>>> > > > >>>>> << :monaLisa dc:creator :leonardo >> > > > >>>>> :startDate "1516"^^xsd:Year. > > > >>>>> > > > >>>>> << > > > >>>>> << :monaLisa dc:creator :leonardo >> > > > >>>>> :startDate "1506"^^xsd:Year > > > >>>>>>> :accordingTo :louvre. > > > >>>>> > > > >>>> > > > >>>>> << > > > >>>>> << :monaLisa dc:creator :leonardo >> > > > >>>>> :startDate "1513"^^xsd:Year > > > >>>>>>> :accordingTo :vezzosi. > > > >>>> > > > >>>> > > > >>>> This represents exactly what we are trying to say, including the > safe date of 1516 and the fact that the two hypothesis are contrasting and > incompatible. > > > >>> > > > >>> But are they? If the 'inner' triples are not being aserted, then > this graph doesn't say anything about the mona lisa at all. It does not > even mention the mona lisa, in fact. But if they are asserted, then yes, we > do have a contradiction, regardless of the :accordingTo annotations. > > > >> > > > >> I see no need to assert the inner triples. In fact, asserting them > would be an error. They MUST NOT be asserted, exactly because they are not > simply true. What we are doing here is not asserting simple facts, it is > not querying simple facts. We are asserting and querying quoted triples. > > > >> > > > >> The triple that is being quoted is NOT ASSERTED (rightly so, > because most probably it is not (simply) true), but the quoted triple > belongs to a triple that IS ASSERTED in a totally legitimate way, it is > simply true, it has a reasonable interpretation (even though it is not > about :monaLisa at all), and is fully compatible with the usual RDF > semantics. > > > >> > > > >> You say: "this graph doesn't say anything about the mona lisa at > all" > > > >> > > > >> This is exactly what makes this triple interesting: it doesn't say > anything about Mona Lisa, yet I can use it (indirectly) to represent > statements detailing information about Mona Lisa, statements that are > time-dependent, contradictory, incomplete, competing with each other, or > plainly bonkers, and all of this while remaining fully within the plain old > RDF semantics. > > > > > > > > Well actually I don't think you can. If it doesn't mention the Mona > LIsa, it doesn't (can't) be understood to be saying anything about it > (her?). You claim to be just using opaque quotation, but you are > interpreting it as though it was transparent. Not to be ad hominem, but > this is a semantic shell game. > > > > > > > >>>> 6) because we can easily deal with non-events and > non-instantaneous events. A non-event is a definite change in state that is > not bound with a specific event. For instance, a politician may be a member > of parliament from the event of the election he was voted in, until the > non-event of failing to obtain a re-election (thank you to my friend Jörge > for mentioning this). > > > >>> > > > >>> But losing an election is just as much an event (well, a 'state of > affairs') as winning one. Non-events are events. > > > >> > > > >> Uhm. Differing sensibilities, I guess. If losing an election is an > event, you should register as events also the facts that several hundreds > of candidates for every parliament seat lost in the same general election, > and not just the incumbent MP. > > > > > > > > That events (or anything else) exist does not obligate anyone to > mention them. There are trees visible in the background of the Mona LIsa, > but we don't have to talk about them. > > > > > > > >> Not particularly efficient. > > > >> > > > >>>> Similarly, a marriage (in its practical, not legal sense) may not > start with a priest or a major and a ceremony and a dinner, but, in these > modern times, simply when two people start seeing each other more often > that others, then progressively exclude anyone else, then start sleeping at > each other places more and more frequently, until they start finding stupid > paying two rents for two places when basically they have been living > together in the one of them for months now, and therefore they let one of > the two contracts expire without renewal. What is then the starting event > of this relationship? The first sex? The first night sleeping together? The > last box moved from the apartment being abandoned? The expiration of the > second rental contract? All of them are lowercase correct starting events, > none of them is uppercase CORRECT. > > > >>> > > > >>> So, it's a complicated world with many blurry edges to our > categories. True, a fundamental issue for any descriptive framework. One > can make similar points about the exact edges of many things. Where exactly > does Mount Everest start? How many lakes are there in Finland? If I am in a > city and I drive out of it, exactly where do I enter the countryside? When > exactly does human life begin? In practice, we impose artificial, legal or > adminstrative boundaries precisely to resolve these kinds of issue cleanly, > to avoid endless disputes. But as I say, this is a general issue, not > something special to events. > > > >> > > > >> My point, exactly. Boundary events are very nice when they clearly > stand out over the others, like births and deaths. Less so when they are > blurred with the background noise of normal life. > > > >> > > > >>>> For instance, the quoted triple > > > >>>> > > > >>>>> << :GustavIII :positionHeld :monarch >> > > > >>>>> :startDate "1771"^^xsd:Year; > > > >>>>> :endDate "1792"^^xsd:Year; > > > >>>>> :for :Sweden; > > > >>>>> :accordingTo :wikipedia; > > > >>>>> :confidence "1.0"^^xsd:decimal. > > > >>>> > > > >>>> is NOT, as you mention, a "muddle between data and metadata", > simply because they are all metadata, and the only data is > > > >>>> > > > >>>>> :GustavIII :positionHeld :monarch > > > >>>> > > > >>>> > > > >>>> What these triples mean is that, simply, in order to assert the > quoted triple you have to constrain the temporal interval to 1771-1792 > > > >>> > > > >>> Which temporal interval? The one being described, or the one in > which the sentence is asserted? Or do you perhaps mean something like a > counterfactual, along the lines of, "If it were a time between 1771 and > 1792 now, then it would be true to assert…"? > > > >> > > > >> You are still trying to make the temporal constraint refer to the > fact being expressed by the quoted triple, or to the time in which the > triple was stated. Neither is true. It is a temporal constraint about the > assertability of the triple. > > > >> > > > >> In practice you are never expected to assert it, since a > temporally-constrained triple is not true in absolute. Yet the temporal > constraint about the quoted triples allow us to make (indirect) assumptions > about the temporal constraints of the inner fact > > > > > > > > HOW? This exposes the shell game clearly. The 'temporal constraint' > is, you claim, on the triple, which is not being asserted and whose content > is irrelevant, just a piece of syntax. Yet this temporal constraint now > appears attached not to a triple, but to an "inner FACT", (my emphasis). > Where did that inner fact come from? I guess somebody INTERPRETED the > triple to get to the fact. What aspect of the RDFstar semantics justified > that move? Perhaps that quotation wan't really a quotation, after all? (And > this gets even less plausible if quotations are nested, BTW.) > > > > > > > >> > > > >>>> , you have to constrain the geographical context > > > >>> > > > >>> What is a geographical context? Context of what? Of an utterance, > or the truth of a sentence, or the location of something in the world? This > is just word-salad until you give it some kind of precise flesh in a > semantic theory. RDF does not mention contexts anywhere, though Guha did > once propose an RDF extension which does. > > > >> > > > >> To clarify, conditions on quoted triples belong to many types. > Their actual semantics is not relevant. > > > > > > > > Of the conditions? Of course it is relevant. > > > > > > > >> The predicates :startFrom and :atLeastSince express temporal > conditions over a quoted triple only because we see in them a temporal > semantics, not because they HAVE a temporal semantics. > > > > > > > > That is meaningless. "See in a temporal semantics" is word-salad. > > > > > > > >> Similarly we could easily write: > > > >> > > > >> << :GustavIII :positionHeld :monarch >> > > > >> :for :Sweden; > > > >> :twas :bryllyg; > > > >> :mimsy "Borogoves". > > > >> > > > >> in order to provide other and more esoteric conditions. They only > matter as conditions of the query necessary to retrieve the quoted triple: > > > > > > > > Not ONLY for querying. They will also be expected to support other > inferences and be used in conjunction with other data. What can you infer > from a nested-quotation triple like the marriage example together with > > > > > > > > :LizTaylor owl:sameAs https://www.wikidata.org/wiki/Q34851 . > > > > > > > > ? I presume, nothing at all. Which is, to put it mildly, a pity. > > > > > > > > How about inferring that if RichardBurton is male then LizTaylor > must be female (because they were married before 2015)? Or that > RichardBurton's date of birth must be earlier than 1945 because one could > not be legally married younger than age 18 in 1963? These are all the kinds > of thing that an OWL reasoner should be able to squeeze out of this data > plus some general facts and a little bit of historical knowledge about > marriage. > > > > > > > >> > > > >> SELECT DISTINCT ?person WHERE { > > > >> << ?person :positionHeld :monarch >> > > > >> :mimsy ?mimsies; > > > >> FILTER (?mimsies IN ("Toves", "Borogoves", "Mome Raths") ) > > > >> } > > > >> > > > >> We need not care to understand that :mimsy means: we do not care > whether this predicate is black or white, as long as it catches the quoted > triples. > > > > > > > > Of course. But this is true of all RDF (RDFS, OWL, etc.) in any > format. One can always assert nonsense, as long as it fits the syntax. So? > > > > > > > >> > > > >>>> to :Sweden, you have to trust the source :wikipedia, and you have > to accept statements with confidence greater or equal to 1.0. They are not > statements about Gustav III, but about the triple :GustavIII :positionHeld > :monarch . > > > >>> > > > >>> So they are all assertions about a syntactic entity? Not even a > proposition? Why then does truth even enter into the discussion? > > > >> > > > >> I do not know. What is a quoted triple? A syntactic entity? A > proposition? Whatever that is, this is what the conditions are assertions > about. I do not want to enter into fine semantic discussions. Whatever > quoted triples are, they are non-asserted triples that I can use as > subjects and objects of asserted triples, and this is something that I can > use to represent constrained or conditional or conjectured statements. > > > >> > > > >>> And by the way, in our earlier example, the different sources > diverged not on the base triple but on another of the annotations (the > date). That is not compatible with what you are claiming here, that all the > meta-triples refer to the base triple, ie in that earlier case the triple > > > >>> > > > >>> :monaLisa dc:creator :leonardo > > > >>> > > > >>> which I assume nobody disputes. > > > >>> > > > >> > > > >> I am not sure I understand this. > > > >> > > > >> > > > >>>> 8) How about repeated occurrences? > > > >>>> > > > >>>>> But in any case, as others have noted, this does not allow for > repeated or interrupted states of affairs, such as the several marriages of > of Dick and Liz, or a judge's status while in recusal. > > > >>>> > > > >>>> The reason it does not allow for repeated states of affairs is > totally due to a specific syntactical choice of RDF* of identifying a > quoted triple rather than an occurrence of the triple. The same problem > arises with all approaches that do not allow an explicit identifier to > their structures, such as quoted graphs in N3. On the contrary, named > graphs are, er... named, and thus their name can be used to differentiate > repeated states of affairs. With named graphs, this becomes trivial: > > > >>>> > > > >>>>>> GRAPH :m1 { :RichardBurton :marriedTo :LizTaylor } > > > >>>>>> GRAPH :m2 { :RichardBurton :marriedTo :LizTaylor } > > > >>>>>> :m1 :startDate "1963"^^xsd:Year; > > > >>>>>> :endDate "1974"^^xsd:Year; > > > >>>>>> :accordingTo :wikipedia; > > > >>>>>> :confidence 1.0. > > > >> > > > >>>>>> :m2 :startDate "1974"^^xsd:Year; > > > >>>>>> :endDate "1975"^^xsd:Year; > > > >>>>>> :accordingTo :wikipedia; > > > >>>>>> :confidence 1.0. > > > >>>> > > > >>>> :m1 and :m2 may have the same content, but are different graphs > and can be identified separately. > > > >>> > > > >>> That RDF is completely nonsensical. > > > >> > > > >> Yes, because named graphs are not allowed to be expressed but not > asserted in rdf-star. > > > >> > > > >>> True, but they have the exact same truthvalue in any RDF > interpretation, and I would expect that to be the case in any future > modifcation or extension to RDF. (If not, how can any valid RDF conclusions > be drawn from any named graph?) So no amount of annotating them is going to > affect what they actually assert. They might have different provenance, of > course, but they cannot be true under different circumstances or true ABOUT > different things, because they are not "about" anything: they are simply > sentences which have a truthvalue and are claimed to be true when asserted. > > > >> > > > >> You are totally right. That is a limit of RDF-star in that it > constrains non-assertion to individual triples and not whole graphs. This > is EXACTLY why I am trying to convince this group to extend the coverage of > rdf-star to include non-asserted named graphs. Once we could do that, an > RDF similar to the one above would become acceptable. > > > >> > > > >> Let me try again with the following example, and using a simple > syntax I just made up. Suppose we have two types of graphs, clearly > separated syntactically, one understood as a container of asserted triples > and the other understood as a container of non-asserted triples: > > > >> > > > >> NON-ASSERTED GRAPH :m1 {{ :RichardBurton :marriedTo :LizTaylor }} > > > >> NON-ASSERTED GRAPH :m2 {{ :RichardBurton :marriedTo :LizTaylor }} > > > >> :m1 :atLeastSince "1963"^^xsd:Year; > > > >> :atMostUpTo "1974"^^xsd:Year; > > > >> :accordingTo :wikipedia; > > > >> :confidence 1.0. > > > >> :m2 :atLeastSince "1974"^^xsd:Year; > > > >> :atMostUpTo "1975"^^xsd:Year; > > > >> :accordingTo :wikipedia; > > > >> :confidence 1.0. > > > >> > > > >> The content of the graphs :m1 and :m2 is NOT ASSERTED, just like > the content of a quoted triple is NOT ASSERTED. Thus said, each of them is > associated to a different set of constraints that clearly allow you to > differentiate and to query each individual marriage, just what we were > trying to do. > > > > > > > > But suppose someone (perhaps by your lights misguided, but following > the RDF semantic intuitions) were to inspect this and assert > > > > > > > > :m1 owl:sameAs :m2 . > > > > > > > > ? After all, they are the same /graph/. You are (mis?)using two > different graph tokens to encode two different events (I know you disagree, > but I think you actually are doing this) but events and triples are not the > same kind of thing and don't have the same identity conditions. > > > > > > > >> > > > >>>> Unfortunately, of course, the semantics of named graphs prevent > us to consider the content of the graph as unasserted. > > > >>> > > > >>> Named graphs allow this, even if RDF* doesn't. At least, the > notion defined in our old paper (which introduced the terminology) does. > https://deliverypdf.ssrn.com/delivery.php?ID=348094069068098092123083121126004024054087061054024018026038100122094066068094114118014088008083029062047001096072094067125023064102015014080098075065064102024126001028031070079119115090&EXT=pdf&INDEX=TRUE. > > > > >>> See section 3.1 > > > >> > > > >> I know and I totally admire this work and I respect what it was > able to obtain. Unfortunately, RDF 1.1 leaves the state of assertedness of > the content of named graphs as unspecified, so, depending on local rules, > they may either be unasserted or simply containers of triples. > > > > > > > > True. Worse, the 'name' (the associated URI label in an RDF dataset) > need not denote or identify the graph it 'names'. My biggest failure in > trying to get the RDF1.1 semantics clear, and a parable of why one should > not let users get hold of something before it is fully defined. > > > > > > > >> > > > >> What I am trying to convey is that we need two types of named > graphs, plain containers of asserted triples and containers of non-asserted > triples, easy to tell apart and use in different ways. > > > > > > > > Sorry, but I can't resist the temptation. See slides starting at 20 > in https://www.slideshare.net/PatHayes/blogic-iswc-2009-invited-talk. > > > > > > > > --------- > > > > > > > > OK, last from me on this topic. Y'all go ahead and I will return to > retirement :-) > > > > > > > >> 2) PREVISION: like it or not, rdf-star quoted triples WILL be used > in this way in the near future in many communities where the need to > express different, competing, reciprocally inconsistent, and/or temporally > constrained statements is particularly pressing. > > > >> > > > > > > > > I am sure you are right, unfortunately. > > > > > > > > Pst > > > > > > > >> Fabio Vitali Tiger got to hunt, bird got > to fly, > > > >> Dept. of Computer Science Man got to sit and wonder "Why, > why, why?' > > > >> Univ. of Bologna ITALY Tiger got to sleep, bird got > to land, > > > >> phone: +39 051 2094872 Man got to tell himself he > understand. > > > >> e-mail: fabio@cs.unibo.it Kurt Vonnegut (1922-2007), > "Cat's cradle" > > > >> http://vitali.web.cs.unibo.it/ > > > >> > > > >> > > > >> > > > >> > > > > > > > > > > > > > >
Received on Wednesday, 5 January 2022 14:07:55 UTC