Historical pe
Thanks Richard and Jeremy for your very useful feedback.
Historical periods obviously need to be localised. "Bronze age" doesn't mean much its own. This can be done using a qualifier in the period name (e.g. "Bronze age, Britain") - the traditional controlled vocabulary approach - but it might be useful to provide a link to a separate place concept as well (which is what the CIDOC CRM requires). The only real difficulty is finding an appropriate way to represent this in SKOS.
Which brings me to Richard's points, all of which are entirely reasonable. The internal data structure does indeed have separate start/end fields, but it's not easy to shoe-horn all these relations into a SKOS representation. SKOS is attractive because of its (relative) simplicity, but it does entail some tradeoffs. Perhaps the answer would be to provide two different formats for the response - SKOS if all that's needed is a simple name-to-time-span translation, and a more complex CRM compatible RDF format for all the messy stuff. The effort involved is not huge, it would depend on the demand - any takers??
The collaborative aspect is also important. Technically, submitting candidates and corrections isn't very difficult to implement. More importantly, and depending on the volume and flakiness of the candidates, it would probably require a maintenance organisation of some sort... CIDOC perhaps.
Richard - I'll get in touch directly concerning the URL rewrites.
Thanks again
Nick
________________________________
From: Richard Light <[log in to unmask]>
To: [log in to unmask]
Sent: Monday, 5 October, 2009 13:43:27
Subject: Re: BC dates [Scanned]
In message <[log in to unmask]
.uk>, "Ottevanger, Jeremy" <[log in to unmask]> writes
> Nice one Nick, that's a brilliant idea. Obviously it's pretty much impossible to get complete consensus on start/end date (or even existence) of all periods, especially those that vary from place to place, but something like this is still really useful.
That's my one reservation about this approach. Nick's thesaurus entry hard-wires a specific date range into the definition of e.g. "Jurassic".
An ideal approach (IMHO) would abstract out the _concept_ of "Jurassic", and then allow assertions to be made about that concept. This approach would accommodate multiple opinions about date ranges, as well as geographically-specific variants.
> I wonder if it could be held in a collaborative environment of some sort.
Something like the Geonames [1] model, perhaps?
> -----Original Message-----
> From: Museums Computer Group [mailto:[log in to unmask]] On Behalf Of Nicholas Crofts
> Sent: 04 October 2009 01:10
> To: [log in to unmask]
> Subject: Re: [MCG] BC dates [Scanned]
>
> The CIDOC conference in Santiago has just finished. One of things we were talking about was a thesaurus of period names that gives start/end time intervals. A lot periods require BCE dates. Geological periods obviously won't fit into the four-digit year ISO standard, so this isn't ISO compatible.
>
> I've been working on an experimental RESTful webservice version that provides data about period names in SKOS format (example below for the term "Jurassic"). This is intended to be machine-readable, so it may look a bit complicated if you're not familiar with SKOS. The service accepts either 'label' or 'id' as a parameter. The label can contain wildcards '%'. The top term is "Eternity".
>
>
> The SKOS "prefLabel" tag contains the period name, the "definition" tag contains the numerical time interval while the "scopeNote" contains a more human friendly version of the interval. Most of the period names, scopeNotes, etc. are in both French and English.
>
> I'd be delighted to have any feedback on this.
Some suggestions:
1. It would be useful to include a link to the Dbpedia concept "Jurassic". Resolving this link gives you the name of the period and a definition in many languages, a list of fossil groups found in this period, etc.
2. While your dates are numeric, they aren't particularly machine-processible. Wouldn't it be better to have separate start- and end-dates, and a duration? In fact, you could use Christian-Emil Ore's date-range algebra [2] to denote the range of possible start-dates and end-dates, using CRM notation
3. As well as the SKOS thesaurus-like relations between periods, wouldn't it be useful to have CRM-like relations ("contains", "falls within") to assert their temporal relationships? (CRM doesn't seem to offer "precedes" and "follows", which would be handy for chaining contiguous periods together.)
4. It would be nice if your resource was a bit closer to the Linked Data model, with simpler URLs being used for each concept (e.g.
http://www.open-world.ch/thesaurus/chrono/3185454
instead of
http://www.open-world.ch/restapi/V2/thesaurus/chrono.php?id=3185454)
This makes them easier for others to quote. You would need a bit of server-side URL rewriting to support this approach.
Richard
[1] http://en.wikipedia.org/wiki/GeoNames
[2] http://cidoc2009.cl/images/documentos/abstracts.pdf, p16-17
-- Richard Light
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