Re: [linking-data] What do the links mean?

(non-exhaustive) summaries of previous discussion on this subject:

----

link semantics is a complex topic ...

To make use of links, you need to understand what those relationships _mean_

What are the common vocabularies that should be used to describe links?

Are the link types particular to a given domain? Is it possible to specify
general purpose definitions? Can domain-specific vocabularies be mapped to
common vocabularies (& if so, how)?

>From the WG email discussion on hypermedia [1]:

* SimonCox: “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”
* RobAtkinson: "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."
* Kerry: "In linked data, the meaning of links is always explicit and
discoverable […]. 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"
* [... a few detailed posts ...]
* SimonCox: "[…] 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"

So when considering "link semantics" we need to square concerns such as:
* helping people choose the right link-type ... owl:sameAs is much
over-used and usually wrong, and when is OK just to use SKOS?
* how to relate our link-types to ''upper ontologies'' - or should we even
try?
* how we can use ontologies ''behind the scenes'' to make sure we don't get
an infinite number of incompatible JSON encodings for the same data

...

@dret's Principles of web data [2] (using a slightly different 5-star
rating than the one we're used to [3]) suggest that "web data" should be:
* (1-star) Linkable
* (4-star) Linked

Issues arising from this are include:
:… use unique, global, _durable_ identifiers
:… need to be able to discover resources so that you can link to them
:… how to assert and maintain links between large sets of resources?
(people are lazy)
:… how are links expressed? (in a doc, in a link header)
:… how are links characterised? (e.g. typing)
:… how are hints about the target resource conveyed?
:… links should be typed (implicitly or explicitly) so that client
applications can decide which links to follow when traversing a web of
interlinked resources to reach application goals

[1]:
https://lists.w3.org/Archives/Public/public-sdw-comments/2015Jul/0002.html
[2]: http://dret.github.io/webdata/
[3]: http://5stardata.info/en/

On Thu, 24 Sep 2015 at 10:39 Frans Knibbe <frans.knibbe@geodan.nl> wrote:

> I don't know if this is the right place to bring this up, but something
> occured to me when I looked at the description of Allen's algebra (used
> for temporal relations): the labels for the relationships have similarities
> with 2D spatial relationships (e.g. the DE-9IM
> <https://en.wikipedia.org/wiki/DE-9IM#Spatial_predicates>). Which perhaps
> is no surprise - isn't Allen's algebra essentialy a way of describing
> events on a line, i.e. a one dimensional space?
>
> At the moment I don't have time for searching for research papers and the
> like, but I wonder if a general model for n-dimensional relationships could
> be used for expressing temporal and spatial relationships. The DE-9IM model
> is for 2D space, but in 1D space (linear referencing) and 3D space there is
> also a need for semantics that describe spatial interaction between
> resources. A single base model could perhaps simplify definition of
> spatiotemporal relationships, lessen the amount of required properties and
> provide extra opportunities for reasoning.
>
> Regards,
> Frans
>
>
>
> 2015-09-24 11:11 GMT+02:00 Ed Parsons <eparsons@google.com>:
>
>> In the spatial domain do we use links to represent spatial relationships
>> of hierarchy (x is constituent part of y) and topology (y is adjacent z) ?
>>
>> ed
>>
>> On Thu, 24 Sep 2015 at 09:33 Jeremy Tandy <jeremy.tandy@gmail.com> wrote:
>>
>>> Email thread for collecting discussion on the question: "What do the
>>> links mean?"
>>>
>>> The related wiki entry for this questions is here [1]
>>>
>>> For instructions about how to engage with this discussion, please see my
>>> previous email [2].
>>>
>>> Many thanks. Jeremy
>>>
>>> [1]:
>>> https://www.w3.org/2015/spatial/wiki/Linking_Data#What_do_the_links_mean.3F
>>>
>>> [2]:
>>> https://lists.w3.org/Archives/Public/public-sdw-wg/2015Sep/0044.html
>>>
>>>
>> --
>>
>> *Ed Parsons*
>> Geospatial Technologist, Google
>>
>> Google Voice +44 (0)20 7881 4501
>> www.edparsons.com @edparsons
>>
>
>