Does "profile of" require all or some elements?

[kcoyle]

From the Shex community: It is also unclear to us whether it is helpful to describe the relation of a profile to its underlying namespaces in terms of a relation of Profile to Standard. The standard-to-profile relation is characterized as one of general-to-specific, but when namespaces simply provide just a handful of their terms to a profile, it seems like a stretch to say that the profile is "profiling" each of the namespaces. https://lists.w3.org/Archives/Public/public-dxwg-comments/2019Feb/0001.html

[kcoyle]

From the profgui meeting of Feb 28:

2. "profile of"
   What conditions entail that one thing is a profile of another thing?
   a. - any use of elements (classes, properties), even if minimal (e.g.
   just use one DC term)[4 - Tom Bakers response]
   b. - use of all of the elements from a "base specification" and possibly
   add elements from another another specification and/or other constraints.
   c. - use of a "significant portion" of a base specification or other
   profile.
   d. - something is a profile of something else if the creator of the
   profile declares it as such

Note that if there is to be any formal inheritance then some of these
definitions would not be usable.

Related issues:
https://github.com/w3c/dxwg/issues/486

https://lists.w3.org/Archives/Public/public-dxwg-wg/2019Mar/0014.html

[kcoyle]

response from Lars:

a. is definitely too weak, d. feels a bit arbitrary. I tend to b. rather than c. even though I understand that there are corner cases where this can be hard. (When it comes to machine-processability I tend towards relatively strict definitions...).

https://lists.w3.org/Archives/Public/public-dxwg-wg/2019Mar/0079.html

[kcoyle]

Response from Makx:

I agree with Lars that b. makes the most sense. For example, the European DCAT-AP mentions each and every property in DCAT-2014 with a usage note. A profile could state "don't use property x" but it should say something about all terms from the specification it is a profile of.

Makx

https://lists.w3.org/Archives/Public/public-dxwg-wg/2019Mar/0080.html

[smrgeoinfo]

I like the approach that

1. a profile is a specification that restricts one or more other specifications in some way.
2. a specification consists of rules/conformance classes/constraints (choose your favorite terminology) that dictate how some particular data resource can be validated as conforming to the specification.
3. A specification is an abstract concept. It is essentially like an FRBR work; there are various manifestations/expressions (maybe @kcoyle can clarify) of the specification as executable rules (shacl, shex, xsd, schematron.......). It's debatable whether these are 'representations' of the specification, or 'related resources'; either approach can work, choose one and be consistent.
4. Data resources that conform to a profile will also validate according to the rules of all base specification for that profile.
5. A profile may use elements from other specifications without inheriting all constraints from those specifications. These are not 'base specifications', they are 'related specifications' (or choose some other relationship terminology that you like). The profile must express any relevant rules for the use of these sort of elements, but that usage must be consistent with constraints from the source specification.

NOTE: edited 2019-03-11 based on subsequent comments by @kcoyle (constraints from related specs) and @makxdekkers (change 'artifact' to 'data resource')

[rob-metalinkage]

@smrgeoinfo .. that is correct and well put.

I think that this might be worth adding into a section on conformance vs reuse.

Only tweak is to make sure people dont confuse artifacts in section 4 with the artifacts used to describe a profile itself.

[makxdekkers]

It is better not to use words that have no clear meaning. 'Artifact' is such a word, basically a synonym for 'Thing'. It is much better to use a less ambiguous word. In the case of @smrgeoinfo's 'particular artifact' in point 2, something like 'data resource' (see my suggestion at https://github.com/w3c/dxwg/issues/572#issuecomment-439384612) or 'instance of a dataset description' could be used.

[kcoyle]

@smrgeoinfo 's #5 seems to be a new concept. Up until now I believe that all use of elements (properties and/or classes) from other vocabularies or profiles implied conformance.

5. "A profile may use elements from other specifications without inheriting conformance constraints from those specifications."

Also, when engaging in inheritance, how would you know which elements do not need to conform?

[smrgeoinfo]

@makxdekkers thanks for that refinement.
@kcoyle the rest of 5 "The profile must express any relevant rules for the use of these sort of elements." is intended to answer that, but it need further thought. I would assume that any domain and range constraints from the original element definition would need to be honored, if they exist.

[kcoyle]

Thanks, @smrgeoinfo. I'm still not sure which (if any) of the definitions on the extent of "profile of" your definition selects. The big question is whether "profile of" implies using an entire specification or something else. The ShEx community response from Tom Baker debated that any profile using a handful of, say, Dublin Core properties mixed in with other namespaces can be said to be a "profile of" Dublin Core. By that definition just about every vocabulary in the Linked Open Vocabularies is a profile of Dublin Core, as is DCAT. So can you say if any of the a.-d. definitions meet yours? Thanks.

[rob-metalinkage]

Were are not talking about reuse or properties, only constraints that have conformance implications. Axioms of the base specification must be respected but option elements remain optional elements unless your profile adds constraints. AFAICT there is no concept "conforms to the whole specification" independent of "is consistent with all constraints". (formal xxioms are a special type of constraint)

[kcoyle]

Rob, the question is different. I think you are responding to @smrgeoinfo 's #5, but above you seemed to agree with it. The question here is which of the options (a-d) laid out by the group do you see as being the meaning of "profile of"? We're trying to get consensus on this.

[smrgeoinfo]

The problem I see is that meaning of 'use of' (in a-c above) is not clear enough to be testable. My interest is to assist client software to select representations of resources from various distributions documented in catalog records. I'm imagining that the metadata record will be able to declare that a distribution conformsTo some profile X, and this statement will be used by client applications to select a distribution that they can work with, the implication being that the representation offered meets certain requirements in terms of vocabularies used, required elements, syntax etc.