Re: How to model valid time of resource properties?

On 2014-10-13 14:14, John Walker wrote:
> Hi Frans,
> See this example:
> http://patterns.dataincubator.org/book/qualified-relation.html

Thank you John! Strangely enough, I had not come across the Linked Data 
Patterns book before. But I can see it is a valuable resource with 
solutions for many common problems. And it looks pretty too! I am sure 
it will come in handy for problems that I haven't stumbled upon yet.

A nice thing about this solution is that it doesn't need any extensions 
of core technologies. I do see some downsides, though:

Let's assume I want to publish data about people, as in the examples. A 
person can have common properties defined by the FOAF vocabulary, like 
foaf:age or foaf:based_near. Properties like these are likely to change. 
If I want to record the time in which a statement is valid I would have 
to create a class for that relationship and add properties to that class 
that will allow me to associate a start time and an end time with the 
class. But by doing that I would not only be forced to create my own 
vocabulary, I would also replace common web wide semantics with my own 
semantics. Or would it still be possible to relate the original property 
with the custom class somehow?

In the cases known to me that require the recording of history of 
resources, /all/ resource properties (except for the identifier) are 
things that can change in time. If this pattern would be applied, it 
would have to be applied to all properties, leading to vocabularies 
exploding and becoming unwieldy, as described in the Discussion paragraph.

I think that the desire to annotate statements with things like valid 
time is very common. Wouldn't it be funny if the best solution to a such 
a common and relatively straightforward requirement is to create large 
custom vocabularies?

Regards,
Frans

> Regards,
>
> John Walker
> Principal Consultant & co-founder
> Semaku B.V.
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>
>> On October 13, 2014 at 1:54 PM Frans Knibbe | Geodan 
>> <frans.knibbe@geodan.nl> wrote:
>>
>> Hello!
>>
>> I wonder if a way of recording changes in properties of resources can 
>> be recommended. Many resources in real life have properties that have 
>> a time range of being valid. In some datasets, only the current (or 
>> most recent) state of a resource is stored, but in many cases it is 
>> important to keep track of the history of development of a resource.
>>
>> An example:
>>
>> :john_smith
>>     a foaf:person ;
>>     foaf:name "John Smith" ;
>>
>> Let's say that on 2013-09-27 John Smith marries Betty Jones. John 
>> Smith is still the same person, so it makes sense to extend the same 
>> resource, not create a new version:
>>
>> :john_smith
>>     a foaf:person ;
>>     foaf:name “John Smith” ;
>>     ex:marriedTo :betty_jones ;
>>
>> How could I efficiently express the fact that the statement 
>> :john_smith ex:marriedTo :betty_jones is valid from 2013-09-27? And 
>> if the couple divorces, that the property has expired after a certain 
>> date? It would be nice if the way of modelling makes it easy to 
>> request the most recent state of a resource, any historical state, or 
>> a list of changes during a time period.
>>
>> A quick web scan on the subject revealed some interesting research 
>> papers, but as far as I can tell all solutions need extensions of RDF 
>> and/or SPARQL to work.
>>
>> Perhaps this question is really about the ability to make statements 
>> about a triple? Which is a problem for which no satisfactory solution 
>> has been found yet?
>>
>> Regards,
>>
>> Frans
>>
>> ------------------------------------------------------------------------
>> Frans Knibbe
>> Geodan
>> President Kennedylaan 1
>> 1079 MB Amsterdam (NL)
>>
>> T +31 (0)20 - 5711 347
>> E frans.knibbe@geodan.nl <mailto:frans.knibbe@geodan.nl>
>> www.geodan.nl <http://www.geodan.nl> | disclaimer 
>> <http://www.geodan.nl/disclaimer>
>> ------------------------------------------------------------------------
>


------------------------------------------------------------------------
Frans Knibbe
Geodan
President Kennedylaan 1
1079 MB Amsterdam (NL)

T +31 (0)20 - 5711 347
E frans.knibbe@geodan.nl
www.geodan.nl <http://www.geodan.nl> | disclaimer 
<http://www.geodan.nl/disclaimer>
------------------------------------------------------------------------