- From: Krzysztof Janowicz <janowicz@ucsb.edu>
- Date: Thu, 1 Sep 2016 14:51:02 -0700
- To: Joshua Lieberman <jlieberman@tumblingwalls.com>, Jeremy Tandy <jeremy.tandy@gmail.com>
- Cc: Frans Knibbe <frans.knibbe@geodan.nl>, SDW WG Public List <public-sdw-wg@w3.org>
- Message-ID: <59d8dd12-5a52-052d-c986-a939fa6a5366@ucsb.edu>
> Feature discernment is a real cognitive process that precedes > representation in data You mean the perceptual and cognitive process of cutting out discrete objects from our sensory fields? Yes, absolutely. In fact, this is among the key issues underlying the so called symbol grounding problem; see Harnad's work. There is some fantastic (and recent) work on how this impacts geo-data interoperability: Scheider, S. (2012). Grounding geographic information in perceptual operations (Vol. 244). IOS Press. Krzysztof On 08/31/2016 10:09 AM, Joshua Lieberman wrote: > >> On Aug 31, 2016, at 12:22 PM, Jeremy Tandy <jeremy.tandy@gmail.com >> <mailto:jeremy.tandy@gmail.com>> wrote: >> >> @josh >> >> > Is the triangle spatial data or a graphic with drawing instructions >> that assumes a certain technology? If 100 people print out the SVG, >> there is really nothing to indicate that the underlying entity is the >> same on each piece of paper, just that the same instructions were >> used, unless we want to get into trademark issues. >> >> This seems to be getting away from the main topic. Unless you object, >> can I pull us back? > > My point is only that if we are dealing with spatial data as feature > data (referencing real world space whether geospatial or not), then > the indirect identification of real world features is on solid > theoretical ground. Otherwise we’re back in the “I know it when I see > it” of general Web content. > >> >> @Krzysztof >> >> Apologies if my terminology is confusing. >> >> I was trying to say that <owl:sameAs> indicates that two identifiers >> (URIs, in this case <http://example.com/sar/features/vo/EDY> and >> <http://example.org/maritime/navaid/2650253>) refer to the same >> entity (Eddystone Lighthouse). You said it much better than me. >> >> The term "representation" was drawn from @josh's email text; in which >> he meant "Eddystone Lighthouse seen as a vertical obstruction" and >> "Eddystone Lighthouse seen as a maritime navigation aid". >> >> >there is no need for such a class [whose members are both vertical >> obstructions and maritime navigation aids] (which you can define if >> you really want to, but it could lead to a combinatorial explosion) >> >> I agree. This is what I've seen with Linked Data implementations - >> which means that "sameRealWorldEntityAs" is not required. >> >> Hmmm. I hope I'm not confusing myself and everyone else. > > Feature discernment is a real cognitive process that precedes > representation in data. It’s a subtle concept, however, and if it’s so > difficult to convey, one might as well deal with the fallout of the > uncommon occasions where it leads to dissonance, rather than > addressing it up front. > > Josh > >> >> Jeremy >> >> On Wed, 31 Aug 2016 at 17:02 Joshua Lieberman >> <jlieberman@tumblingwalls.com <mailto:jlieberman@tumblingwalls.com>> >> wrote: >> >>> On Aug 31, 2016, at 10:20 AM, Frans Knibbe >>> <frans.knibbe@geodan.nl <mailto:frans.knibbe@geodan.nl>> wrote: >>> >>> >>> >>> On 31 August 2016 at 13:42, Joshua Lieberman >>> <jlieberman@tumblingwalls.com >>> <mailto:jlieberman@tumblingwalls.com>> wrote: >>> >>> If we are asserting that spatial data on the Web is "always" >>> feature data that represents a real world entity, then yes, >>> we don't have the general Web "is it or isn't it physical" >>> ambiguity and can assume that a feature data identifier also >>> and indirectly identifies the feature. >>> >>> >>> I hope we can broaden that assumption, that the assertion still >>> holds even if we are not talking about feature data representing >>> real world entities. >>> >>> Let's look at a border case: I am drawing a triangle in Inkscape >>> and I save it as a *.svg file. I publish the file on the web, so >>> it has a URI. Now I would say the triangle is a spatial thing >>> (not sure if it counts as a real world entity, but I hope we can >>> leave the idea of 'real world' out of definitions anyway). The >>> SVG object in the file is the geometry describing the spatial >>> thing. I think that only if we understand the SVG file to be the >>> spatial thing we get into trouble. I might want to state that >>> the file has a certain size and that the triangle has a certain >>> area. It would be funny if I used the same URI for both >>> statements. So I would need to have a different URI for my >>> triangle. Could that be all? >> >> Is the triangle spatial data or a graphic with drawing >> instructions that assumes a certain technology? If 100 people >> print out the SVG, there is really nothing to indicate that the >> underlying entity is the same on each piece of paper, just that >> the same instructions were used, unless we want to get into >> trademark issues. >> >>> That still leaves a gap in expressing whether two feature >>> data entities represent the same real world entity. Perhaps >>> we need a "sameFeatureAs" predicate to address this. >>> >>> >>> Yes, that is what the Subject equality >>> <http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#SubjectEquality> >>> requirement is about. So the BP document is expected to say >>> something about that. >>> >>> Regards, >>> Frans >>> >>> >>> Josh >>> >>> Joshua Lieberman, Ph.D. >>> Principal, Tumbling Walls Consultancy >>> Tel/Direct: +1 617-431-6431 <tel:%2B1%20617-431-6431> >>> jlieberman@tumblingwalls.com >>> <mailto:jlieberman@tumblingwalls.com> >>> >>> On Aug 31, 2016, at 07:29, Frans Knibbe >>> <frans.knibbe@geodan.nl <mailto:frans.knibbe@geodan.nl>> wrote: >>> >>>> Hello, >>>> >>>> As stated before, I don't think the httpRange-14 problem >>>> exists in our domain of discourse. I think (and hope) that >>>> confusion can only occur when the things that are described >>>> are digital things, or things that can be transmitted over >>>> a computer network, like web pages or mail boxes. It seems >>>> to me that spatial things are never that type of thing. >>>> Therefore there is no reason to take precautions against >>>> possible confusion. >>>> >>>> That probably means +1. >>>> >>>> Greetings, >>>> Frans >>>> >>>> >>>> On 31 August 2016 at 09:50, Jeremy Tandy >>>> <jeremy.tandy@gmail.com <mailto:jeremy.tandy@gmail.com>> wrote: >>>> >>>> Thanks Rob & Clemens ... >>>> >>>> On Wed, 31 Aug 2016 at 08:30, Clemens Portele >>>> <portele@interactive-instruments.de >>>> <mailto:portele@interactive-instruments.de>> wrote: >>>> >>>> +1 >>>> >>>> >>>> On 30 August 2016 at 10:10:26, Jeremy Tandy >>>> (jeremy.tandy@gmail.com >>>> <mailto:jeremy.tandy@gmail.com>) wrote: >>>> >>>>> Hi. It would be good to close this issue out & >>>>> include our collective recommendation in the BP >>>>> doc working draft. >>>>> >>>>> PROPOSAL: SDW working group recommends use of >>>>> "indirect identifiers" for spatial things >>>>> >>>>> ... I'll start the voting. >>>>> >>>>> +1 >>>>> >>>>> Jeremy >>>>> >>>>> (BTW, to make sense of the PROPOSAL you'll need to >>>>> read the email thread) >>>>> >>>>> On Fri, 26 Aug 2016 at 10:12 Linda van den Brink >>>>> <l.vandenbrink@geonovum.nl >>>>> <mailto:l.vandenbrink@geonovum.nl>> wrote: >>>>> >>>>> So… do we agree we can recommend indirect >>>>> identifiers, or do we try to fix the issue >>>>> with getting the correct identifier as Rob >>>>> describes? >>>>> >>>>> >>>>> While waiting for this I’ve updated the issue >>>>> and the text referring to the issue in BP6. >>>>> >>>>> >>>>> *Van:* Rob Atkinson >>>>> [mailto:rob@metalinkage.com.au >>>>> <mailto:rob@metalinkage.com.au>] >>>>> *Verzonden:* woensdag 24 augustus 2016 13:56 >>>>> *Aan:* Jeremy Tandy; Phil Archer; Linda van >>>>> den Brink; Bill Roberts >>>>> >>>>> >>>>> *CC:* SDW WG Public List >>>>> >>>>> *Onderwerp:* Re: Clarification required: BP6 >>>>> "use HTTP URIs for spatial things" >>>>> >>>>> >>>>> Hi >>>>> >>>>> >>>>> Agree this is a real concern - people cant be >>>>> blamed for doing the obvious, if dumb, thing.. >>>>> >>>>> >>>>> I think we should take note of best practice >>>>> in the HTML world - which is often to include >>>>> a citable link to a resource in the rendered >>>>> view. Or a "share" or something similar. We >>>>> can also put fairly explicit annotation in >>>>> machine-readable code - stating that the >>>>> resource is about the URI - and even notes >>>>> saying when citing this resource use the URI.... >>>>> >>>>> >>>>> I'd also like to see browsers evolve to offer >>>>> you the original link or the redirected when >>>>> cutting and pasting - how hard can it be! >>>>> >>>>> >>>>> Maybe we can get Ed to ask around Google >>>>> Chrome team for suggestions on how best to >>>>> handle this :-) >>>>> >>>>> >>>>> Rob >>>>> >>>>> >>>>> >>>>> >>>>> On Wed, 24 Aug 2016 at 18:27 Jeremy Tandy >>>>> <jeremy.tandy@gmail.com >>>>> <mailto:jeremy.tandy@gmail.com>> wrote: >>>>> >>>>> Yes, I think so ... And we should do so if >>>>> we are recommending "indirect identification". >>>>> >>>>> Jeremy >>>>> >>>>> On Wed, 24 Aug 2016 at 09:24, Phil Archer >>>>> <phila@w3.org <mailto:phila@w3.org>> wrote: >>>>> >>>>> Bill's comments also made me think >>>>> about some of the classic arguments, >>>>> such as that a lake doesn't have a >>>>> last updated date and isn't 435KB >>>>> big. Which are true, however, that >>>>> kind of metadata generally comes from >>>>> the server, i.e. the HTTP layer. >>>>> That's an over simplification but the >>>>> point is that it is relatively easy to >>>>> avoid deliberately creating >>>>> misleading metadata - metadata about >>>>> the doc rather than the thing it >>>>> describes - and it's also generally >>>>> easy to avoid looking for that metadata. >>>>> >>>>> Is there scope for some BP advice there? >>>>> >>>>> Phil. >>>>> >>>>> On 24/08/2016 08:25, Jeremy Tandy wrote: >>>>> > Thanks Linda. More clear examples >>>>> where being "correct" (in terms of >>>>> > avoiding uri collisions by using two >>>>> distinct uris) is making things worse >>>>> > because users take the wrong one! >>>>> > >>>>> > So, as a WG, are we content to >>>>> recommend this "indirect identification" >>>>> > pattern where thing & info resource >>>>> identifiers are conflated? >>>>> > >>>>> > Bill has added some good points >>>>> about how to avoid impacts of uri >>>>> > collision- by using the (dataset) >>>>> metadata to talk about licenses and >>>>> > creators for the information ... >>>>> > On Wed, 24 Aug 2016 at 07:52, Linda >>>>> van den Brink >>>>> <l.vandenbrink@geonovum.nl >>>>> <mailto:l.vandenbrink@geonovum.nl>> >>>>> > wrote: >>>>> > >>>>> >> Experience from the Netherlands: we >>>>> have the id/doc pattern in our URI >>>>> >> strategy, based on the Cool URIs >>>>> note [8] and the ISA study on persistent >>>>> >> identifiers [9]. >>>>> >> >>>>> >> >>>>> >> >>>>> >> That being said, same as Bill I >>>>> also notice data users getting confused >>>>> >> and generally using the /doc/ URI >>>>> as that is the one they can copy from >>>>> >> their browser address bar. This is >>>>> not only casual confusion but also ends >>>>> >> up in published information resources. >>>>> >> >>>>> >> >>>>> >> >>>>> >> You see this, for example, all over >>>>> the CB-NL which is a vocabulary for >>>>> >> the building sector and contains >>>>> links to other Dutch standards such as >>>>> >> IMGeo, an information model and >>>>> vocabulary for large scale topography. >>>>> E.g. >>>>> >> the CB-NL concept of ‘Gebouw’ >>>>> (Building) [10] links to two IMGeo >>>>> concepts >>>>> >> ‘Pand’ (building part) and ‘Overig >>>>> Bouwwerk’ (other construction) using >>>>> >> their /doc/ URIs. If you click on >>>>> Pand (which doesn’t have its own landing >>>>> >> page in CB-NL so I can’t include >>>>> the link) you will see it includes the >>>>> >> /doc/ URI as the identifier of Pand. >>>>> >> >>>>> >> >>>>> >> >>>>> >> This is an example where it occurs >>>>> in vocabularies, but I also see it >>>>> >> happen with identifiers for data >>>>> instances. >>>>> >> >>>>> >> >>>>> >> >>>>> >> [8]: https://www.w3.org/TR/cooluris/ >>>>> >> >>>>> >> [9]: >>>>> >> >>>>> https://joinup.ec.europa.eu/sites/default/files/D7.1.3%20-%20Study%20on%20persistent%20URIs_0.pdf >>>>> >> 10: http://ont.cbnl.org/cb/def/Gebouw >>>>> >> >>>>> >> >>>>> >> >>>>> >> Linda >>>>> >> >>>>> >> >>>>> >> >>>>> >> *Van:* Jeremy Tandy >>>>> [mailto:jeremy.tandy@gmail.com >>>>> <mailto:jeremy.tandy@gmail.com>] >>>>> >> *Verzonden:* dinsdag 23 augustus >>>>> 2016 20:57 >>>>> >> *Aan:* Bill Roberts >>>>> >> *CC:* SDW WG Public List >>>>> >> *Onderwerp:* Re: Clarification >>>>> required: BP6 "use HTTP URIs for spatial >>>>> >> things" >>>>> >> >>>>> >> >>>>> >> >>>>> >> Thanks Bill. Sounds very coherent >>>>> ... I hoped for some responses such as >>>>> >> this based on practical experience. >>>>> Jeremy >>>>> >> >>>>> >> On Tue, 23 Aug 2016 at 19:41, Bill >>>>> Roberts <bill@swirrl.com >>>>> <mailto:bill@swirrl.com>> wrote: >>>>> >> >>>>> >> ah Jeremy, you are a brave man to >>>>> poke the sleeping beast of httpRange-14. >>>>> >> >>>>> >> >>>>> >> >>>>> >> But I'll get my thoughts in early, >>>>> then I can tune out of the ensuing mail >>>>> >> avalanche :-) >>>>> >> >>>>> >> >>>>> >> >>>>> >> When publishing Linked Data about >>>>> places we (at Swirrl) generally do the >>>>> >> id/doc fandango, but to be honest I >>>>> think data users either don't notice, >>>>> >> or they get confused by it. In the >>>>> applications we are working with (and I >>>>> >> acknowledge that others may have >>>>> different applications and different >>>>> >> experiences), it wouldn't cause any >>>>> problems to have a single URI, the 'id' >>>>> >> URI if you like. We just don't find >>>>> a need to say anything about the /doc/ >>>>> >> URI. If we were starting again, I'd >>>>> probably ditch the /doc/ and the 303 >>>>> >> and rely on context and a little >>>>> bit of documentation to make it clear what >>>>> >> we mean. >>>>> >> >>>>> >> >>>>> >> >>>>> >> The place where we find a need to >>>>> talk about creators and licences and >>>>> >> modified dates is in metadata about >>>>> datasets where a dataset might be a >>>>> >> collection of information about a >>>>> bunch of places - and we treat datasets >>>>> >> as an 'information resource'. If >>>>> someone requests a dataset URI we return a >>>>> >> status code of 200 and the dataset >>>>> metadata as the response. That metadata >>>>> >> includes info on where to get all >>>>> the contents of the dataset if you want >>>>> >> that. >>>>> >> >>>>> >> >>>>> >> >>>>> >> By the way, though it's sensible >>>>> and consistent, I find that the implied >>>>> >> and parallel property stuff makes >>>>> it more rather than less complicated. >>>>> >> >>>>> >> >>>>> >> >>>>> >> Bill >>>>> >> >>>>> >> >>>>> >> >>>>> >> >>>>> >> >>>>> >> >>>>> >> >>>>> >> >>>>> >> >>>>> >> >>>>> >> >>>>> >> >>>>> >> >>>>> >> On 23 August 2016 at 17:37, Jeremy >>>>> Tandy <jeremy.tandy@gmail.com >>>>> <mailto:jeremy.tandy@gmail.com>> wrote: >>>>> >> >>>>> >> All- >>>>> >> >>>>> >> >>>>> >> >>>>> >> Linda has done a great job of >>>>> consolidating the best practices are >>>>> use of >>>>> >> identifiers. We have just one [1] now. >>>>> >> >>>>> >> >>>>> >> >>>>> >> Reading though just now, it >>>>> occurred to me that there's still an open >>>>> >> issue about identifier assignment ... >>>>> >> >>>>> >> >>>>> >> >>>>> >> W3C's Architecture of the World >>>>> Wide Web constraint "URIs identify a >>>>> >> single resource" [2] asserts >>>>> "Assign distinct URIs to distinct >>>>> resources" >>>>> >> in order to avoid URI collisions >>>>> [2a] which "often imposes a cost in >>>>> >> communication due to the effort >>>>> required to resolve ambiguities". >>>>> >> Discussions from earlier years in >>>>> UK Gov Linked Data working group (and >>>>> >> elsewhere) concluded that the "real >>>>> world thing" and "information resource >>>>> >> that describes the real world >>>>> thing" are separate resources. I think >>>>> this >>>>> >> is based on a (purist?) view when >>>>> working with RDF of needing to be totally >>>>> >> clear on "what's the subject" of >>>>> each triple ... the thing or the document. >>>>> >> This manifests as URIs with `id` or >>>>> `doc` included somewhere to distinguish >>>>> >> between the resources and some RDF >>>>> triples to clarify that the doc resource >>>>> >> is talking about the thing resource >>>>> etc.. >>>>> >> >>>>> >> >>>>> >> >>>>> >> (dangerously close to >>>>> "httpRange-14" [3] here ... let's >>>>> avoid that bear >>>>> >> trap) >>>>> >> >>>>> >> >>>>> >> >>>>> >> Jeni Tennison's "URLs in Data >>>>> Primer" draft TAG note captures this >>>>> >> practice in §5.3 "Publishing data" [4]: >>>>> >> >>>>> >> >>>>> >> >>>>> >> ``` >>>>> >> >>>>> >> Publishers can help enable more >>>>> accurate merging of data from different >>>>> >> sites if they support URLs for each >>>>> entity >>>>> >> >>>>> <https://www.w3.org/TR/urls-in-data/#dfn-entity> >>>>> they or other sites may >>>>> >> wish to describe, separate from the >>>>> landing pages >>>>> >> >>>>> <https://www.w3.org/TR/urls-in-data/#dfn-landing-page> >>>>> or records >>>>> >> >>>>> <https://www.w3.org/TR/urls-in-data/#dfn-record> >>>>> that they publish. >>>>> >> >>>>> >> ``` >>>>> >> >>>>> >> >>>>> >> >>>>> >> Yet Architecture of the World Wide >>>>> Web §2.2.3 "Indirect identification" >>>>> >> [5] notes that: >>>>> >> >>>>> >> >>>>> >> >>>>> >> ``` >>>>> >> >>>>> >> To say that the URI >>>>> "mailto:nadia@example.com >>>>> <mailto:nadia@example.com>" identifies >>>>> both an >>>>> >> Internet mailbox and Nadia, the >>>>> person, introduces a URI collision. >>>>> >> However, we can use the URI to >>>>> indirectly identify Nadia. Identifiers are >>>>> >> commonly used in this way. >>>>> >> >>>>> >> ``` >>>>> >> >>>>> >> >>>>> >> >>>>> >> This is consistent with what I >>>>> recall TimBL saying at TPAC-2015 in >>>>> regards >>>>> >> to Vcard; come the finish, no one >>>>> really cares to distinguish between the >>>>> >> thing and its associated >>>>> information resource. >>>>> >> >>>>> >> >>>>> >> >>>>> >> ... And in most cases, one can use >>>>> context to determine whether a >>>>> >> statement concerns the thing or the >>>>> information resource. In those cases >>>>> >> where you can't, "URLs in Data >>>>> Primer" suggests some mechanisms to >>>>> mitigate >>>>> >> such confusion [6][7]. >>>>> >> >>>>> >> >>>>> >> >>>>> >> I think that in our SDW WG >>>>> discussion we have concluded that we _are_ >>>>> >> content to use "indirect >>>>> identification" - e.g. that we use >>>>> URIs that >>>>> >> conflate the thing and document >>>>> resource. >>>>> >> >>>>> >> >>>>> >> >>>>> >> Please can we confirm this? >>>>> Assuming that indirect identification is >>>>> >> "approved" as best practice, then >>>>> it seems prudent to add a note to the BP >>>>> >> document saying "don't worry about >>>>> distinguishing between thing and >>>>> >> resource; indirect identification >>>>> is fine" (etc.) >>>>> >> >>>>> >> >>>>> >> >>>>> >> Thanks, Jeremy >>>>> >> >>>>> >> >>>>> >> >>>>> >> [1]: >>>>> http://w3c.github.io/sdw/bp/#globally-unique-ids >>>>> >> >>>>> >> [2]: >>>>> https://www.w3.org/TR/webarch/#pr-uri-collision >>>>> >> >>>>> >> [2a]: >>>>> https://www.w3.org/TR/webarch/#URI-collision >>>>> >> >>>>> >> [3]: >>>>> https://www.w3.org/2001/tag/group/track/issues/14 >>>>> >> >>>>> >> [4]: >>>>> https://www.w3.org/TR/urls-in-data/#publishing-data >>>>> >> >>>>> >> [5]: >>>>> https://www.w3.org/TR/webarch/#indirect-identification >>>>> >> >>>>> >> [6]: >>>>> https://www.w3.org/TR/urls-in-data/#documenting-properties >>>>> >> >>>>> >> [7]: >>>>> https://www.w3.org/TR/urls-in-data/#authoring-specifications >>>>> >> >>>>> >> >>>>> >> >>>>> >> >>>>> > >>>>> >>>>> -- >>>>> >>>>> >>>>> Phil Archer >>>>> W3C Data Activity Lead >>>>> http://www.w3.org/2013/data/ >>>>> >>>>> http://philarcher.org >>>>> <http://philarcher.org/> >>>>> +44 (0)7887 767755 >>>>> <tel:%2B44%20%280%297887%20767755> >>>>> @philarcher1 >>>>> >>>> >>> > -- 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, 1 September 2016 21:51:39 UTC