Re: UCR issue 26

Hello Chris,

It is pity your message was stuck in limbo for a while, but I think it is
still a very useful contribution. Sapporo may have passed, but work on the
OWL Time deliverable has not begun yet.

This seems to be yet another example of us needing to have a common
understanding of semantics. Would it be possible to add the concepts you
describe to our informal glossary of terms
<https://www.w3.org/2015/spatial/wiki/Glossary_of_terms>? And would it be
possible to refer to official definitions of those terms, if they exist?

For me, as a temporal layman, it would be helpful to have examples of each
class. For example. the geological time scale
<https://en.wikipedia.org/wiki/Geologic_time_scale>, the three-age system
<https://en.wikipedia.org/wiki/Three-age_system>, UNIX time
<https://en.wikipedia.org/wiki/Unix_time>, the Chronology of the universe
<https://en.wikipedia.org/wiki/Chronology_of_the_universe> or the Conventional
Egyptian chronology
<https://en.wikipedia.org/wiki/Egyptian_chronology#Conventional_chronology>:
in which one of the four classes would they fit in?

Regards,
Frans




2015-11-06 12:47 GMT+01:00 Little, Chris <chris.little@metoffice.gov.uk>:

> I think this email was trapped in limbo in a temporary outbox for the last
> fortnight. Hope it hasn’t missed the  boat, but probably has as Sapporo has
> passed.
>
>
>
> Dear Frans and others
>
>
>
> One thing that I would like to insert into the discussion here is
> clarification of terminology that we are going to use in the Best Practice
> (and these discussion of the issues).
>
>
>
> Below is “Temporal Reference System”. Is this the same as a ‘Temporal
> Coordinate Reference System’ or even ‘Temporal System’? Components of such
> systems include: Instants, durations, periods, events, counts, calendars,
> notations, axes, datum/epochs, Units of Measure, …. .
>
>
>
> At one level, there is an unwritten but valid requirement to be consistent
> with the  terminology and structures of the spatial reference systems
> (which perhaps partially answers Bill’s query as to why are we doing time?).
>
>
>
> Unless any one can suggest alternatives, preferably pre-existing, here are
> my suggestions for what we a talking about, based on my presentation to the
> SDWWG recently and the OGC Temporal Domain WG:
>
>
>
> 0.       Temporal System: notation, events, relations/operators
>
> 1.       Temporal Reference System: notation, relations/operators,
> clocks, counts
>
> 2.       Temporal Coordinate Reference System: notation,
> relations/operators, instants , durations, UoM, Axis, Epoch
>
> 3.       Calendar: notation, units, periods, origin (epoch?),
> underpinning TRS or TCRS, algorithms.
>
>
>
> I think a lot of confusion has been caused by using entities from one
> ‘regime’ in another.
>
>
>
> HTH but it might not, Chris
>
>
>
> *From:* Frans Knibbe [mailto:frans.knibbe@geodan.nl]
> *Sent:* Monday, October 26, 2015 12:02 PM
> *To:* Alejandro Llaves
> *Cc:* Heaven, Rachel E.; SDW WG Public List; Jon Blower; Simon Cox
>
> *Subject:* Re: UCR issue 26
>
>
>
>
>
>
>
> 2015-10-21 12:07 GMT+02:00 Alejandro Llaves <allaves@fi.upm.es>:
>
> Hi Frans,
>
>
>
> C&P your proposal:
>
>
>
> *'It should be possible to make use of possibilities of temporal reference
> systems to express components of time at various levels of precision. *
>
>
>
> *This requirement expresses the need to be able to handle vague, imprecise
> or uncertain time. Some examples are "early 1950s", "late Jurassic",
> "during the reign of Khafra", "the afternoon of July 1st". It should be
> noted that uncertainty in time does not need to be restricted to the
> highest precision time component in an expression of time. For instance, a
> photograph might be known to be taken on Christmas day, but the year in
> which the photograph was taken could be uncertain.''*
>
>
>
> The first sentence sounds too complex to me. I don't get the part of "to
> make use of possibilities of temporal reference systems".
>
>
>
> Some Temporal Reference Systems (TRS) have possibilities of expressing
> time at various levels of precision. ISO-8601 for example allows
> "2015-10-26" and "2015-10". The requirement is for OWL Time to not restrict
> the freedom in expressions of time that some TRSs allow. Does this make
> sense? I guess it would help if we add an example like 2015-10-26" versus
> "2015-10".
>
>
>
> And "it should be possible to make use of possibilities" is a bit
> redundant.
>
>
>
> I don't know... the first possibilities should be in OWL Time and the
> second are the possibilities in TRSs. I think those are different
> possibilities, so it will be hard to remove one of them. But could you
> suggest clearer phrasing?
>
>
>
>
>
> I like the second part with the examples ;) Maybe, it would make more
> sense using "to be able to represent/describe" instead of "to be able to
> handle", but I can live with both.
>
>
>
> OK, I changed "handle" to "describe". Perhaps the part with the examples
> could be extended with explanations:
>
>
>
> *This requirement expresses the need to be able to describe vague,
> imprecise or uncertain time. Some examples are:*
>
>    - * ISO 8601 expressions "2012-10-23T23:46" versus "2012-10-23" versus
>    "2012-10"*
>    - *"early 1950s"*
>    - *"later part of the Jurassic"*
>    - *"during the reign of Khafra"*
>    - *"the afternoon of July 1st" (the year is unknown)*
>
> *It should be noted that uncertainty in time does not need to be
> restricted to the highest precision time component in an expression of
> time. For instance, a photograph might be known to be taken on Christmas
> day, but the year in which the photograph was taken could be uncertain.'*
>
>
>
> Suddenly I am not sure if the example "during the reign of Khafra" is
> appropriate. The timing could be uncertain because there is no indication
> of the definition of the reign of Khafra. Different egyptologists may have
> different dates for that period, and I think those different definitions
> would be different TRSs. But if a time is unclear because the TRS is
> absent, that would be another matter than the one this requirement is
> concerned with.
>
>
>
> Perhaps we should remove this example. Or change it to "around the the
> reign of Khafra"?
>
>
>
> Greetings,
>
> Frans
>
>
>
>
>
> Thanks!
>
> Alejandro
>
>
>
> On 21 October 2015 at 00:13, <Simon.Cox@csiro.au> wrote:
>
> Ø  Perhaps a new version of OWL time will be based on the idea that
> instants are actually intervals too?
>
>
>
> OWL-Time does take this position already. It follows Allen’s theory, which
> make intervals the primary structure, and instants a special case where we
> can’t distinguish the beginning and end, at the current level of precision.
>
>
>
> *From:* Frans Knibbe [mailto:frans.knibbe@geodan.nl]
> *Sent:* Tuesday, 20 October 2015 10:28 PM
> *To:* Heaven, Rachel E. <reh@bgs.ac.uk>; SDW WG Public List <
> public-sdw-wg@w3.org>
> *Cc:* Jon Blower <j.d.blower@reading.ac.uk>
>
>
> *Subject:* Re: UCR issue 26
>
>
>
> Hello all,
>
>
>
> The photo from Christmas day is a nice example. I think we should add a
> few examples to this requirement and the Christmas day photo should be one
> of those.
>
>
>
> So here is a new proposal:
>
>
>
> *'It should be possible to make use of possiblities of temporal reference
> systems to express components of time at various levels of precision.*
>
>
>
> *This requirement expresses the need to be able to handle vague, imprecise
> or uncertain time. Some examples are "early 1950s", "late Jurassic",
> "during the reign of Khafra", "the afternoon of July 1st". It should be
> noted that uncertainty in time does not need to be restricted to the
> highest precision time component in an expression of time. For instance, a
> photograph might be known to be taken on Christmas day, but the year in
> which the photograph was taken could be uncertain.'*
>
>
>
> I did change ''..express time" to "...express components of time", but
> here the distinction between intervals and instants from Rachel's proposal
> is not made. I am not sure such a distinction is necessary. Perhaps a new
> version of OWL time will be based on the idea that instants are actually
> intervals too?
>
>
>
> Greetings,
>
> Frans
>
>
>
>
>
>
>
> 2015-10-09 17:52 GMT+02:00 Heaven, Rachel E. <reh@bgs.ac.uk>:
>
> The vagueness (e.g. “before 1972” or “early 1950s”, or even “the end of
> the Jurassic”) can usually be expressed by an interval with a different
> precision on each end, or an undefined start or end.  “Afternoon of June
> 1st” is an interval with a precise start time and a less precise end,
> depending on culture and season...
>
>
>
> Then there are the other examples where one component of the date might be
> known very precisely (a photo from Christmas day), but the year is known
> with less certainty.
>
>
>
> So perhaps:
>
> 'It should be possible to make use of possibilities of temporal reference
> systems to express components of time instants and components of time
> intervals at various levels of precision'.
>
>
>
> Regards,
>
> Rachel
>
>
>
> *From:* Frans Knibbe [mailto:frans.knibbe@geodan.nl]
> *Sent:* 09 October 2015 14:25
> *To:* Jon Blower
> *Cc:* SDW WG Public List
> *Subject:* Re: UCR issue 26
>
>
>
> Hi Jon,
>
>
>
> Yes, I think this is about temporal precision. For Gregorian time it is
> possible to have different precisions in ISO 8601: 2003-04-27T23:45 is more
> precise than 2003-04-27, which is more precise than 2003. I don't think
> playing with precision like this is possible with XSD datatypes, especially
> when one is limited to xsd:dateTime.
>
>
>
> Other temporal reference systems have precision too. For example, in
> geological time 'Paleogene' is more precize than 'Cenozoic'.
>
>
>
> That would bring me to a requirement like 'It should be possible to make
> use of possiblities of temporal reference systems to express time at
> various levels of precision'.
>
>
>
> Regards,
>
> Frans
>
>
>
> 2015-10-08 17:38 GMT+02:00 Jon Blower <j.d.blower@reading.ac.uk>:
>
> Hi Frans,
>
>
>
> I see your point (both examples could be seen as extremely precise,
> depending on our expectations and application).
>
>
>
> Maybe instead of calling the requirement “temporal vagueness” it should be
> “temporal precision”, the requirement being to be able to express the
> precision of a time value.
>
>
>
> Cheers,
>
> Jon
>
>
>
> On 8 Oct 2015, at 15:59, Frans Knibbe <frans.knibbe@geodan.nl> wrote:
>
>
>
> Hello,
>
>
>
> This is a thread for trying to resolve UCR issue 26
> <https://www.w3.org/2015/spatial/track/issues/26>. Again, the issue deals
> with clarification of a requirement. In this case it is about the OWL Time
> requirement Temporal vagueness
> <http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#TemporalVagueness>
> .
>
>
>
> Current phrasing is: *"It should be possible to describe time points and
> intervals in a vague, imprecise manner. For instance, to represent an event
> happened on the afternoon of June 1st or at the second quarter of the 9th
> century."*
>
>
>
> The examples seem to be neither vague nor imprecise. Could other examples
> be supplied, or could be explained why the examples are vague and/or
> imprecise?
>
>
>
> Especially the time specialists among us: please help in getting this
> requirement in shape.
>
>
>
> Greetings,
>
> Frans
>
>
>
>
>
>
>
>
> ------------------------------
>
> This message (and any attachments) is for the recipient only. NERC is
> subject to the Freedom of Information Act 2000 and the contents of this
> email and any reply you make may be disclosed by NERC unless it is exempt
> from release under the Act. Any material supplied to NERC may be stored in
> an electronic records management system.
> ------------------------------
>
>
>
>
>
>
>
> --
>
> Alejandro Llaves
>
> Ontology Engineering Group (OEG)
>
> Artificial Intelligence Department
>
> Universidad Politécnica de Madrid
>
> Avda. Montepríncipe s/n
>
> Boadilla del Monte, 28660 Madrid, Spain
>
>
>
> http://www.oeg-upm.net/index.php/phd/325-allaves
>
>
>
> allaves@fi.upm.es
>
>
>