Re: Our approach to unasserted assertions is ambiguous and lossy [ was: Re: streamlining the baseline]

On 7/1/24 15:03, Thomas Lörtsch wrote:
> 
> 
> Am 1. Juli 2024 20:04:32 MESZ schrieb "Peter F. Patel-Schneider" <pfpschneider@gmail.com>:
>> On 7/1/24 12:18, Thomas Lörtsch wrote:
>>>
>>>
>>> Am 1. Juli 2024 16:05:45 MESZ schrieb "Peter F. Patel-Schneider" <pfpschneider@gmail.com>:
>>>> I do not understand this entire line of argument at all.
>>>
>>> I do not understand yours.
>>>
>>> For starters: which graphs? I didn't use graphs in my examples. RDF named graphs? Out of scope as I learned in response to my Nested Named Graphs proposal last autumn. So your technique of separating realms of validity employed below has no representation in RDF.
>>
>> RDF is nothing without graphs.  In particular, assertion can only be understood with reference to an RDF graph - without a graph there is no notion of assertion.  Named graphs are simply graphs, with their own asserted triples.
> 
> RDF named graphs have no semantics. I have no idea what kind of graphs your curly btacket syntax refers to. Anyway my examples didn't use graphs for goid reason. By introducing some underspecified notion of graphs you changed they topic, and then declared victory. I think that's not helpful.

RDF named graphs do indeed have semantics - they are RDF graphs and thus have 
all their semantics.  An RDF graph is a set, so I used {} notation to indicate 
a set of triples, as is quite normal.

And RDF graphs do have a well-defined semantics - see 
https://www.w3.org/TR/rdf12-semantics/

What you might be alluding to is that references to RDF named graphs don't 
have semantics.   But they do have semantics in RDF graphs, just not one that 
is very useful.

> 
>>> And what about qualified statements a la Wikipedia? How do you propose to express those with the means of RDF-star? Or is that a different problem in your opinion?
>>
>> RDF-star has no notion of qualified statements.   There are only triples. Embedded triples can be used to implement qualified statements (more or less) but the meaning of this implementation comes from RDF not from anything that is not part of RDF.
>>
>> Embedded triples change nothing about assertion.  It is still the case that a triple is either in an RDF graph - and thus true or asserted in that graph - or not in an RDF graph - and thus not asserted in that graph.
>>
>> That said, a way to implement qualified statements from Wikidata uses a triple whose subject is linked to the embedded triple corresponding to the main snak, whose predicate is the predicate of the qualifying snak, and whose object is the value of the qualifying snak.
> 
> And then, how is that embedded triple specified? Maybe you should read my mail again.

Just like any other embedded triple is specified.   So if you want to 
represent the given names of Douglas Adams you would create an RDF graph 
containing the following triples (using the well-known Wikidata RDF prefixes):

wd:Q42 wdt:P735 wd:Q463035 .
_:a rdf:reifies (embedded wd:Q42 wdt:P735 wd:Q463035 .)
_:a wdt:P1545 1 .
_:a wdt:P3831 wd:Q3409033 .

wd:Q42 wdt:P735 wd:Q19688263 .
_:a rdf:reifies (embedded wd:Q42 wdt:P735 wd:Q19688263 .)
_:a wdt:P1545 2 .

Here I am just using (embedded ...) for embedded triples instead of any of 
they proposed syntaxes.

> 
> Best,
> Thomas
> 
> 
>> peter
>>
>>
>>>> The idea seems to be that there is a fundamental difference between the two uses of rdf:reifies in the two RDF graphs
>>>> {
>>>>     _:x rdf:reifies (embedded P) .
>>>> }
>>>> and
>>>> {
>>>>     _:y rdf:reifies (embedded P) .
>>>>     P
>>>> }
>>>>
>>>> So that there is a need for two different relationships in the RDF namespace as in
>>>> {
>>>>     _:x rdf:cites (embedded :Moon :madeOf :Cheese );
>>>>         :reportedBy :Alice .
>>>> }
>>>>
>>>> {
>>>>     _:y rdf:asserts (embedded :Moon :madeOf :Cheese ) ;
>>>>         :claimedBy :Bob .
>>>>     :Moon :madeOf :Cheese .
>>>> }
>>>>
>>>> because in one case :Bob is claming that the embedded triple is true but the other case :Alice is merely reporting on the embedded triple without claiming that it is true.
>>>>
>>>>
>>>> But there is no reason to assert the embedded triple just because :Bob is making a claim about it, nor is there any reason to use different relationships to the embedded triple just because the reifier is used in different ways.
>>>>
>>>> That is rdf:reifies is adequate for both
>>>>
>>>> {
>>>>     _:x rdf:reifies (embedded :Moon :madeOf :Cheese );
>>>>         :reportedBy :Alice .
>>>> }
>>>>
>>>> {
>>>>     _:y rdf:reifies (embedded :Moon :madeOf :Cheese ) ;
>>>>         :claimedBy :Bob .
>>>>     :Moon :madeOf :Cheese .
>>>> }
>>>>
>>>> whether or not
>>>>
>>>>     :Moon :madeOf :Cheese .
>>>>
>>>> is also asserted in the same RDF graph or there are other reports or claims about the same triple in that graph.
>>>>
>>>> peter
>>>>
>>

Received on Monday, 1 July 2024 19:42:23 UTC