Re: Blog post about "Provenance in RDF-star"

Hi Anthony,

On 27/01/2022 10:13, Anthony Moretti wrote:
> Hi Pierre-Antoine
>
> Thank you for the post.
>
>     It is however important to understand that this basic design has
>     limitations. Namely, each statement made about a particular triple
>     must be interpretable independently of the other statements made
>     about that triple. (This is actually a general feature of RDF, not
>     just RDF-star: two statements about the same subject must always
>     be interpretable independently from each other. On the open web,
>     if we assume that another triple that we have not yet discovered
>     could change the meaning of the triples that we know, then
>     reasoning with what we know would become much more hazardous.)
>
>
> I don't know if I'm right, but I feel like this is highly related to 
> the idea of statements being "simply true", as people have put it. To 
> go back to the first email in the "Three ideas" thread, I feel like 
> time, space, and confidence/certainty are the three annotations that 
> make any statement "simply true", i.e. make any statement able to 
> stand alone as a complete unit of description. It's definitely 
> possible that I haven't thought deeply enough about this, if so, maybe 
> someone can show me a counterexample where all those annotations are 
> specified and the entire statement is not "simply true". But if I'm 
> right, and these annotations are special, they should be given 
> precedence and asserted first to avoid ambiguity like that described 
> in the blog post.

I think the two discussions are orthogonal.

The post is about using the RDF-star model, as specified by the CG 
report, and about the common pitfalls that people should avoid with this 
model.

The "three ideas" thread (as well as your answer below) is about a 
potential alternative model, where time, space and confidence would 
become core components of statements. Of course, in this different 
model, the examples of the post would be modeled differently. And yes, 
the pain points in one model will not be the same as the pain points in 
the other model.

Note also that I disagree with the way you rephrase the examples from 
the blog post into your new model, see below.

>
> To further simplify things, time, space, and certainty could be three 
> positions, rather than four, if the temporal range is given typical 
> "range" syntax:
>
> Subject Relation Object [T1, T2] SpatialBound Certainty
>
> Any datatype that makes sense for certainty/confidence can be used in 
> the last position.
>
> Then, with those three positions, the examples in the blog post could 
> be modified like so:
>
> *Original extended first example:*
>
> << :employee38 :jobTitle "Assistant Designer" >>
>     :accordingTo :employee22, :employee38 ;
>     :confidence 0.8 .
>
> Would become:
>
> << :employee38 :jobTitle "Assistant Designer" _ _ "0.8"^^ex:confidence >>
>     :accordingTo :employee22, :employee38 .

It may be me misinterpreting your alternative model, but I don't think 
that the two examples are conveying the same meaning. Let me rephrase in 
plain English how I interpret them.

1st example :

"I am 80% certain that emp38 is an assistant designer, as claimed by 
emp22 and emp38"
(confidence is asserted by me)

2nd example

"emp22 and emp38 both claim that they are 80% certain that emp38 is an 
assistant designer"
(confidence is asserted by emp22 and emp38 respectively)

>
> *Original problematic example:*
>
> << :employee38 :jobTitle "Assistant Designer" >>
>     :accordingTo :employee22; :confidence 0.2 .
>     # we don’t trust employee22 about someone else’s job title
>
> << :employee38 :jobTitle "Assistant Designer" >>
>     :accordingTo :employee38; :confidence 0.8 .
>     # we quite trust employee38 about their own job title
>
> Would become:
>
> << :employee38 :jobTitle "Assistant Designer" >>
>     :accordingTo :employee22 _ _ "0.2"^^ex:confidence .
Which I read as

"I am 20% confident that emp22 said that emp38 is an assistant designer"
(confidence is about :accordingTo)

while the intended meaning was

"I am 20% confident in emp22's claim that emp38 is an assistant designer"
(confidence is about :jobTitle)

>
> << :employee38 :jobTitle "Assistant Designer" >>
>     :accordingTo :employee38 _ _ "0.8"^^ex:confidence .
>
> *It's easy to see what a more complex example might look like:*
>
> << :employee38 :jobTitle "Assistant Designer" _ _ "0.8"^^ex:confidence >>
>     :accordingTo :employee22 _ _ "0.2"^^ex:confidence .
>
> << :employee38 :jobTitle "Assistant Designer" _ _ "0.8"^^ex:confidence >>
>     :accordingTo :employee38 _ _ "0.8"^^ex:confidence .
>
> Those three positions can be added to the other statement types I 
> described, and the whole system becomes consistent, scalable, and easy 
> to reason about.

unless I missed something, we have not yet discussed about how your 
alternative model could be reasoned about. Nor should be do that before 
a clear semantics of the statements is described...

   best


> Apologies for being repetitive, but I really think the holistic 
> approach has a lot of benefits.
>
> Regards
> Anthony
>
> On Thu, Jan 27, 2022 at 8:13 AM Kingsley Idehen 
> <kidehen@openlinksw.com> wrote:
>
>     On 1/26/22 3:34 PM, Pierre-Antoine Champin wrote:
>>     Dear all,
>>
>>     following a discussion during our two last calls, I published a
>>     post about "Provenance in RDF-star":
>>
>>     https://www.w3.org/community/rdf-dev/2022/01/26/provenance-in-rdf-star/

>>
>>
>>     quoting the intro:
>>
>>     > In this post, we present some lessons learned by the group
>>     through discussions and exchanges. This is meant to give some
>>     insight about the rationale behind RDF-star, and some guidelines
>>     about how to best use it for modeling provenance data.
>>
>>     Many thanks to all the participants of the RDF-star group for
>>     their reviews and feedback on this post.
>>
>>       pa
>>
>
>     Hi Pierre-Antoine,
>
>     An opening example in that blog post:
>
>     PREFIX : <http://www.example.org/> <http://www.example.org/>
>
>     << :employee38 :jobTitle "Assistant Designer" >>
>         :accordingTo :employee22, :employee38 ;
>         :confidence 0.8 .
>
>     My variant using RDF as it exists.
>
>     ## RDF-Turtle Start ##
>
>     # PREFIX : <http://www.example.org/> <http://www.example.org/>
>     PREFIX schema: <http://schema.org/> <http://schema.org/>
>     PREFIX : <#>
>
>     [
>       :jobTitle "Assistant Designer" ;
>       schema:identifier :employee38  # if desired,
>     inverse-functional-property semantics can be applied to the
>     schema:identifier relation.
>     ] :accordingTo :employee22, :employee38 ;
>       :confidence 0.8 .
>
>     ## RDF-Turtle End ##
>
>     What is the difference between both? Is it that your RDF-Star
>     example expresses a statement (*utterance*) while mine expresses a
>     fact (*proposition*)?
>
>     "A *statement* occurs at a particular time and place.  But a
>     *fact* is independent of time and place." [1]
>
>
>     Links:
>
>     [1]
>     https://groups.google.com/d/msgid/ontolog-forum/d37df77c62aa4cdab97ad92a30821600%40bestweb.net

>     -- John F. Sowa post about statements and facts
>
>
>     -- 
>     Regards,
>
>     Kingsley Idehen 
>     Founder & CEO
>     OpenLink Software
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