[Crm-sig] P90 etc.

Conal Tuohy conal.tuohy at gmail.com
Wed Mar 14 12:01:29 EET 2018


On 9 March 2018 at 04:39, Martin Doerr <martin at ics.forth.gr> wrote:

>
>
> I recommend NOT to recommend rdf:value, because RDFS 1.1 defines:
> "5.4.3 rdf:value rdf:value is an instance of rdf:Property
> <https://www.w3.org/TR/rdf-schema/#ch_property> that may be used in
> describing structured values. rdf:value has no meaning on its own. "
>
> As CRM-SIG, we cannot recommend a property without meaning. We do ontology
> here, so the must be a minimal ontological commitment. Are there other
> opinions?
>

My opinion is that the real value of rdf:value is that it effectively
negates one of the weaknesses in the expressiveness of RDF, with respect to
the CRM.

In RDF, a literal value is a second-class citizen: it has no identifier,
which makes it ineligible to appear as the subject of a triple, so it can't
have properties of its own. It can't be woven into the "Web of Data". It
can't effectively function as an "access point" (in the library science
sense) without some additional context.

As Linked Data practitioners, we generally have literals like "Conal Tuohy"
as our source data for e.g. Appellations (and it's worth noting that all of
the formal examples of E41 Appellation are given as string literals), but
it's highly undesirable to encode an E41 Appellation merely as a literal;
such an encoding would make it impossible, either for us, or for third
parties, to annotate that name with properties of its own ("A name of Irish
origin ...").

So we must mint an identifier, either a local ("blank node") identifier --
or better still, an HTTP URI -- for that name (e.g. "_conal_tuohy"), so
that we can then attach other properties to that identifier. We are left,
finally, with the residual problem of how to associate the literal name
value itself ("Conal Tuohy") with that identifier. This is where rdf:value
plays a valuable role of effectively just equating the literal with
identifier; it is described as having "no meaning on its own" precisely
because it really plays only a syntactical role. This is why I think it
would be a mistake to critique the use of rdf:value on the basis of it
"lacking meaning of its own"; it would be equivalent to criticising a
relational database for having an Appellation table with a column named
"value".

Regards

"Conal Tuohy"




> Taken the above definition in RDFS 1.1, I question both, the precise use
> and the emerging good practice,
> until better evidence:-).
> Do you have better evidence?
>
> It is up to crm-sig to decide, I present only my opinion here.
>
> Best,
>
> martin
>
>
>
> On 3/8/2018 6:28 PM, Robert Sanderson wrote:
>
>
>
> Martin,
>
>
>
> Could you clarify why you have changed your mind about rdf:value?
>
>
>
> > I recommend NOT to recommend rdf:value
>
>
>
> In particular, in the last week you said:
>
>
>
> “CRM-SIG normally works reactively: When a good community practice
> emerges, this is taken up.”
>
>
>
> and
>
>
>
> “Whatever the vast majority is  and rdf:value does the job, I have no
> objections to its use.
> Just define precisely what you use it for. We can add that to our
> guidelines. It is already standard rdf.”
>
>
>
> Thanks,
>
>
>
> Rob
>
>
>
>
>
>
> --
> --------------------------------------------------------------
>  Dr. Martin Doerr              |  Vox:+30(2810)391625        |
>  Research Director             |  Fax:+30(2810)391638        |
>                                |  Email: martin at ics.forth.gr |
>                                                              |
>                Center for Cultural Informatics               |
>                Information Systems Laboratory                |
>                 Institute of Computer Science                |
>    Foundation for Research and Technology - Hellas (FORTH)   |
>                                                              |
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> --------------------------------------------------------------
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-- 
Conal Tuohy
http://conaltuohy.com/
@conal_tuohy
+61-466-324297
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