Dave, hello. On 2011 Oct 20, at 22:31, Dave Reynolds wrote:
>>> Benefit 2: Conceptual cleanliness and hedging your bets >>> >>> [...]Even if we can't spot the practical problems right now >>> then differentiating between the galaxy itself and some piece of data >>> about the galaxy could turn out to be important in practice. >> >> It is. I want to say that 'line 123 in this catalogue [an existing RDBMS] >> and line 456 in that one both refer to the same galaxy, but they give >> different values for its surface brightness'. There's no way I can >> articulate that unless I'm explicitly clear about the difference between a >> billion suns and a database row. [...] > Perhaps benefit 2 could be reframed as being about forcing you to > confront the map/territory distinction so you end up doing better > modelling - whether or not you implement 303s. I think that's _very_ true. Perhaps one can say that any "information architect" should understand the IR/NIR distinction, however they subsequently decide to represent this. > I think the discussion Leigh was trying to start was "can we more > clearly article those benefits of the 'right way'". I was taking a shot > a that, maybe a very limited off-target one. While I think it's very important to be clear about precisely what one's URIs refer to, I'm starting to wonder if the benefits of the 'right way' (which is the IR/NIR and 200/303 distinction, right?) really are all that massive. I think your listing of the costs and benefits <http://lists.w3.org/Archives/Public/public-lod/2011Oct/0158.html> is a useful summary. > Most people I > talk to grok the distinction, the hard bit is understanding why 303 > redirects is a sensible way of making it and caring about it enough to > put those in place. Yes: it's becoming clearer to me that this is what the discussion is really about, even though it started off being about the lament "why don't people understand this distinction?". ---- You also commented on ways to represent observational data. > (1) Describe the observations explicitly using something like ISO O&M or > the DataCube vocabulary: > > <http://catalogue1.com/observation123> a qb:Observation; > eg:galaxy <http://iau.org/id/galaxy/m31>; > eg:brightness 6.5 ; > eg:obsdate '2011-10-10'^^xsd:date ; > qb:dataset <http://catalogue1.com/catalogue/2011> . > > <http://catalogue2.com/observation456> a qb:Observation; > eg:galaxy <http://iau.org/id/galaxy/m31>; > eg:brightness 6.8 ; > eg:obsdate '2011-09-01'^^xsd:date ; > qb:dataset <http://catalogue2.com/catalogue/2011> . > > (2) Each catalogue gives its own URI to its "understanding" of the > galaxy so it can assert things directly about it without conflict: > > <http://catalogue1.com/galaxy/m31> eg:brightness 6.5; > eg:correspondsTo <http://iau.org/id/galaxy/m31> . > > <http://catalogue2.com/galaxy/m31> eg:brightness 6.8; > eg:correspondsTo <http://iau.org/id/galaxy/m31> . For huge numbers of objects, the _only_ name they have is their number in some observational catalogue or other -- there's no canonical IAU name. In a current project, we're setting up the support to be able to say <http://catalogue1.com/galaxy/123> cat1:brightness xxx. <http://catalogue2.com/galaxy/456> cat2:brightness yyy. <http://catalogue1.com/galaxy/123> owl:sameAs <http://catalogue2/galaxy/456>. We probably also want to reify the database rows where the first two statements come from, in order to make last-modified-like statements about them, but whether we do that with a named graph, or some other way, is a problem we haven't had to confront quite yet. > In *none* of those cases doesn't it make any difference whether when I > dereference <http://iau.org/id/galaxy/m31> in a browser I get a web page > saying "I denote the galaxy M31" or I get a 303 redirect to something > like <http://iau.org/doc/galaxy/m31> which in turn connegs to a web page > saying "The URI you started with denoted the galaxy M31, me I'm just a > web page, you can tell me by the way I walk". Well, I think it does matter, because in this case, the thing named <http://catalogue1.com/galaxy/123> could plausibly be either the galaxy or the database row (and I suppose I could claim the latter as a NIR, with a following wind), and I'd need to be able to state, somewhere, which it is. But that's handled by my providing some RDF somewhere which explains which it is: the problem is how to get to that RDF without drawing some ambiguous or wrong conclusions on the way. Best wishes, Norman -- Norman Gray : http://nxg.me.uk SUPA School of Physics and Astronomy, University of Glasgow, UK
