- From: Krzysztof Janowicz <janowicz@ucsb.edu>
- Date: Thu, 30 Jul 2015 11:15:29 -0700
- To: <public-sdw-comments@w3.org>
- Message-ID: <55BA69C1.7090308@ucsb.edu>
Hi, > In linked data, the meaning of links is always explicit and > discoverable-- that is the fundamental reason for the use of formal > vocabularies. This also applies to owl:sameAs and rdf:seeAlso, > although quite purposefully, rdfs:seeAlso has rather weak semantics. > On the other hand, owl:sameAs has very tight semantics, but is very > commonly used in a way that violates those semantics. Agreed, but let's not forget that only a very few of them such as owl:sameAs and rdfs:subProperty have a formal semantics. This makes a big compared to seeAlso and many popular SKOS relations. > I doubt we can do much about the latter in the broader linked data > world, unfortunately. Maybe we can; our work and recommendations will have a broad visibility. > Curious as to how we might be able to "late-bind" to upper ontologies, > and dissapointed there isnt a Use Case proposed that deals with two > bodies of data implemented as RDF using different upper ontology > choices. It seems to be this is something we really dont have a good > solution to talk to yet. I could try to write such a Use Case, but > i'll probably get the terminology all wrong and offend everyone (again). IMHO, patterns largely replace the need for upper ontologies and I would rather not define alignments to such top-level ontologies anymore. Best, Krzysztof On 07/30/2015 12:00 AM, Rob Atkinson wrote: > > I would agree there is a need to actually verify the "goodness" of > some "best practices" - rather than just assert that utopia is coming. > We need to walk semantics, not talk it, now. When something that is > convincing to us, and can be shown to be tractable to developers is > available, then the talk can resume. > I dont think we need to throw out formal ontologies to get convenient > JSON data - we should use the ontologies behind the scenes to make > sure we dont get an infinite number of incompatible json renderings of > the same data! > Likewise, we should not throw out existing data models and standards > governance when building those ontologies. In many cases we simply cant. > Curious as to how we might be able to "late-bind" to upper ontologies, > and dissapointed there isnt a Use Case proposed that deals with two > bodies of data implemented as RDF using different upper ontology > choices. It seems to be this is something we really dont have a good > solution to talk to yet. I could try to write such a Use Case, but > i'll probably get the terminology all wrong and offend everyone (again). > > > On Thu, 30 Jul 2015 at 15:39 <Simon.Cox@csiro.au> wrote: > > Don’t get me wrong – precise link semantics is important. That’s > why I prefer time:hasTRS and geom:hasCRS to dct:conformsTo (the > latter was suggested on a dcat list in the last week). > > Maybe it’s the people I’ve been meeting recently, but I’m finding > it still necessary to establish the more basic principles > (fine-grained well-managed URIs, hypertext). Mention of RDF and > semantic web technologies too esoteric for most web developers, > who only know JSON. Depending on the audience, a softly-softly > approach is essential, so we must calibrate our discourse overall > so we don’t overwhelm them until they are ready. We should > practice amongst ourselves, and not gratuitously talk semantics > until it is specifically required. > > I’m basically supporting Erik’s position – let’s make sure > hypertext is on the table first. > > Simon > > *From:*Rob Atkinson [mailto:rob@metalinkage.com.au > <mailto:rob@metalinkage.com.au>] > *Sent:* Thursday, 30 July 2015 1:38 PM > *To:* Kerry Taylor <Kerry.Taylor@acm.org > <mailto:Kerry.Taylor@acm.org>>; Rob Atkinson > <rob@metalinkage.com.au <mailto:rob@metalinkage.com.au>> > *Cc:* Cox, Simon (L&W, Highett) <Simon.Cox@csiro.au>; > dret@berkeley.edu <mailto:dret@berkeley.edu>; > jeremy.tandy@gmail.com <mailto:jeremy.tandy@gmail.com>; > public-sdw-comments@w3.org <mailto:public-sdw-comments@w3.org>; > eparsons@google.com <mailto:eparsons@google.com> > > > *Subject:* Re: adding hypermedia to spatial data best practices > > Do agree - i will submit a Use Case from the Hydrology domain > where the link semantics are critical, and not supported by an > existing vocabulary. > > my thinking is that best practices relate to the use of RDF > because we can have flexibility, and make things explicit, but > then we need to choose one or all of: > > 1) strong but generalised semantics - for example spatial > relationships > > 2) strong and domain-specific semantics required to process data > in the context of the domain - for example a relationship between > a building and a property, or between a hydrological catchment and > an upstream catchment > > 3) weak semantics (where human mediation is probably required - > but i suppose deeper discovery of resources could be envisioned) > > hopefully a best practice can discuss the pros and cons of each of > these, provide examples and importantly shed some light on the > practicalities of governance of such vocabularies. If we can > indeed fit this neatly into the existing 5-star system it should > provide a greater sense of how and why "linked data" applies to > geospatial information, and we can then perhaps look at the > specific case of hypermedia in this context - is it a weak > semantics for the link - or is it in fact supposed to support some > automated traversal, and if so what is required to do so. > > Rob > > On Thu, 30 Jul 2015 at 12:55 Kerry Taylor <Kerry.Taylor@acm.org > <mailto:Kerry.Taylor@acm.org>> wrote: > > All, > > In linked data, the meaning of links is always explicit and > discoverable-- that is the fundamental reason for the use of > formal vocabularies. This also applies to owl:sameAs and > rdf:seeAlso, although quite purposefully, rdfs:seeAlso has > rather weak semantics. On the other hand, owl:sameAs has very > tight semantics, but is very commonly used in a way that > violates those semantics. I doubt we can do much about the > latter in the broader linked data world, unfortunately. > > What we *can* do in this group is to advise on using linking > vocabulary that is well-defined and, if we cannot find such > vocabulary already, to create and define whatever is missing > in the spatial space( did I really write that?). I did not > see much in our use cases that suggests new vocabulary is > needed, except perhaps in the area of informal spatial > relations, where there is no geometry and maybe even very > fuzzy location. I hope that our best practice advice will > serve to reduce confusion and encourage publishers to respect > the intended semantics of the vocabulary we advise. > > I admit to confusion about what 'hyperlinks' and related > 'hypermedia' means in this discussion. Is it about links > between remote resources only? Or about links within "media" > like video, interactive maps etc ( stuff that is not text or > data).? In any case linked data is all about typed links , ie > links with meaning, whether internal or remote. > > The fifth star does not change the meaning of the links at > all, it only asks publishers to explicitly include some links > to remote resources > > -Kerry > > > On 29 Jul 2015, at 3:38 pm, Rob Atkinson > <rob@metalinkage.com.au <mailto:rob@metalinkage.com.au>> wrote: > > Personally, I think the relationship between "data" and > "hyperlinking" needs some greater care. In a > self-contained database, relationships are a first-class > concern - however there is a prevalence in the linked data > world of using ad-hoc approaches to generating hyperlinks > - for example using owl:sameAs to link to an interactive > mapping application via geographical coordinates. using > very general link semantics "rdf:seeAlso" for links to > related data is another common pattern. The lack of a > demonstrably good practice is fairly hard to reconcile > with any potential to be able to use such links in any > automated fashion, so the development of best practice > discussion and exemplar resources is an important step to > take. fortunately, the Linked Data web is still tiny > compared to the problem space, so there is not a huge > amount invested in sub-optimal approaches. > > I think a "star" that matters is missing - which is to > make the meaning of hyperlinks explicit and discoverable - > this is far more useful than putting the data into RDF per > se, but one could argue thats the underlying intent of > using RDF, in that such links have URIs for link > predicates - and there is an implication regarding what > those URIs should resolve to. Maybe there is some good > practice out there somewhere of how to hyperlink without > losing information or adding more noise to the system we > could point to - but I haven't seen one in the geospatial > domain. > > Rob Atkinson > > On Wed, 29 Jul 2015 at 11:11 <Simon.Cox@csiro.au > <mailto:Simon.Cox@csiro.au>> wrote: > > Hmm. That's interesting that you mention the coupling > of 'specific model' with 'linked data'. We must be > careful about bringing the 5th-star into play too > soon. Linked data relies first on (i) stable, > resolvable URIs, (ii) open formats, and (iii) > hyperlinks, so let's make sure that message gets > across first and is not buried in premature focus on > semantics. > > -----Original Message----- > From: Erik Wilde [mailto:dret@berkeley.edu > <mailto:dret@berkeley.edu>] > Sent: Wednesday, 29 July 2015 9:53 AM > To: Jeremy Tandy; public-sdw-comments@w3.org > <mailto:public-sdw-comments@w3.org> > Cc: Ed Parsons > Subject: Re: adding hypermedia to spatial data best > practices > > hello jeremy. > > On 2015-07-27 02:44, Jeremy Tandy wrote: > > As one of the editors for the Best Practice doc, I > will read through > > the two resources you cite in the hope that there > will be less for me > > to write :-) ... seriously though, I will review and > match your work > > against our formative requirements. Holiday season > is upon us so rate > > of progress might be a little slow ... > > no worries. and seriously from my side, i'd love to > get feedback and even requests for more detailed > content for both resources. i see a lo0t on confusion > in the spectrum between linked data (which mandates a > specific model that not everybody necessarily wants to > use) and no guidance in which case the hypermedia > aspect (imho the biggest value proposition of the web > by far, when combined with REST's uniform interface > constraint) often gets forgotten. thus my attempt to > talk about "web data" that focuses on what makes the > web valuable, without prescribing a specific path to > realize that value. > > thanks and cheers, > > dret. > > -- > erik wilde | mailto:dret@berkeley.edu > <mailto:dret@berkeley.edu> - tel:+1-510-2061079 | > | UC Berkeley - School of Information > (ISchool) | > | http://dret.net/netdret > http://twitter.com/dret | > -- Krzysztof Janowicz Geography Department, University of California, Santa Barbara 4830 Ellison Hall, Santa Barbara, CA 93106-4060 Email: jano@geog.ucsb.edu Webpage: http://geog.ucsb.edu/~jano/ Semantic Web Journal: http://www.semantic-web-journal.net
Received on Thursday, 30 July 2015 18:16:07 UTC