[VEP-003]: datalink/core#sibling

[Markus Demleitner]

Hi DAL, again,

On Fri, Dec 06, 2019 at 02:45:30PM +0100, ada nebot wrote:
> But if were to add terms such as sibling and so on, there is already an IVOA relationship vocabulary: 
> http://ivoa.net/rdf/voresource/relationship_type/2016-08-17/relationship_type.html <http://ivoa.net/rdf/voresource/relationship_type/2016-08-17/relationship_type.html>
> 
> Comments? 

This is an excellent point.  relationship_type currently reflects the
parts of DataCite's relationships relevant to VOResource.  But these
relationships by DataCite's goals are also (indeed, mainly) intended
for what we in the VO would call datasets.  And that happens to be
rather close to what Datalink is talking about.

I also agree it looks a bit odd that we have #IsDerivedFrom and 
#IsSourceOf in relationship_type and #progenitor and #derivation in
datalink/core -- it's one of these cases where things that appear to
be largely unrelated (Registry and Datalink) suddenly turn out to
have rather close relations after all.

On the other hand, of course, I'm always for pragmatism when in
doubt.  The main use case for Datalink semantics has been (or so I
think) to let clients filter out or group links depending on what
they perceive the current user interest (which I think so far none
do): Hide #progenitor in science analysis, hide #derivation during
debugging.

For that, #progenitor and #derivation would, I think, work rather
well (though I'm suddenly not sure any more why #calibration isn't a
child of #progenitor -- if someone puts in a VEP for that, I think
you'd have my vote).  And anyway, before we embark on a re-design of
that part of datalink with a view to unifying it with VOResource, I'd
frankly like to have opinions from datalink consumers if they'd like
a move towards relationship_type.

So, I guess what I'm saying is: as long as we have #derivation and
#progenitor in datalink/core, there should be #sibling.  This at
least appears attractive to me from a producer side (which, yes,
isn't more than half the picture).

The alternative would be to deprecate #derivation and #progenitor and
devise some way to pull relationship_type into Datalink.  I give you
that'd certainly be cleaner.  But, as said above, my
pragmatism-o-meter currently has an underflow when considering that.
But, again, it's been known to be off before.

        -- Markus


PS: Incidentally, vocabularies should be cited with the namespaces
given on their HTML renditions, in this case
http://www.ivoa.net/rdf/voresource/relationship_type and
http://www.ivoa.net/rdf/datalink/core.  I wonder if there's a good
way to encourage people to not just yank the URL out of their
browser...