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RE: ISSUE 14: temporal reasoning and relations

From: Little, Chris <chris.little@metoffice.gov.uk>
Date: Wed, 5 Aug 2015 12:42:06 +0000
To: Karl Grossner <karlg@stanford.edu>, Frans Knibbe <frans.knibbe@geodan.nl>, SDW WG Public List <public-sdw-wg@w3.org>
Message-ID: <3DAD8A5A545D7644A066C4F2E82072883E179213@EXXCMPD1DAG4.cmpd1.metoffice.gov.uk>
Frans, Karl,

To add some more info here.

Last year, the OGC Temporal Domain WG produced a discussion paper on the underlying (mathematical) problems with instants and intervals, that would make a good basis for any ‘uncertainty interval algebra’ extending the work of the Allen operators, which are the temporal equivalent (<,>,=, etc)

People seem prone to re-inventing the Allen operators, including consistent or inconsistent subsets.

The Temporal DWG has also been working on an OGC Temporal Best Practice document, but we’ve been spread too think this last year.

Basically, it will warn and hopefully educate people that time is harder than they think, as stated by Saint Augustine 1500 years ago. The premises of the document are:

1.       Several Temporal Regimes, not to be mixed up willy-nilly:
Events, Allen operators, no clocks, no CRS, no calendar;
Clocks, ticks, integer counts, no interpolation or extrapolation;
CRS, interpolating and extrapolating integer clock counts to the real number line;
Calendars: beware! Leap days, leap seconds, months, weeks, intercalations, astronomy, etc.


2.       Notation, such as those in ISO8601



3.       Inconsistencies in existing standards from OGC, ISO, ITU, IETF, OASIS, OMG, CENLEC, IEEE, WMO, etc.


HTH, Chris

From: Karl Grossner [mailto:karlg@stanford.edu]
Sent: Tuesday, August 04, 2015 4:57 PM
To: Frans Knibbe; SDW WG Public List
Subject: Re: ISSUE 14: temporal reasoning and relations


Hello,



Don't know whether or how this may be useful in the business of SDW; I've been largely absent from the group due to timing of meetings:



Use Case 4.17 states, "There is no framework available to describe fuzzy temporal information." There are, however two nascent efforts that will accommodate 'fuzziness' in varying degree: the Periods, Organized project [1] and Topotime [2]. In both cases, timespans can be described not only by pairs of instants, but also by pairs of intervals. This pattern has appeared elsewhere (e.g. in the SIMILE Timeline software). Additionally, Topotime includes operators like before (<), after (>), and about (~), and differentiates 'some time/duration within' and 'throughout.' It is currently in active (re-)development as a GeoJSON extension [3].



All phenomena occurring at a location have temporal attributes of co-equal importance (which isn't to say we always know them, or care, or that people aren't prone to using spatial snapshots). But general models of natural phenomena should permit representing their most important characteristics, including the 'where' and 'when' of them. What motivates Topotime is that in historical data we are very frequently representing entities with shapes and positions that change over time, and for which spatial-temporal extents are uncertain in various ways.



Happy to discuss further - in or out of this thread :^)



Karl



[1] http://perio.do


[2] http://dh.stanford.edu/topotime


[3] https://github.com/kgeographer/topotime





--
Karl Grossner, PhD
Center for Interdisciplinary Digital Research
Stanford University Libraries
http://kgeographer.org

________________________________
From: Frans Knibbe <frans.knibbe@geodan.nl<mailto:frans.knibbe@geodan.nl>>
Sent: Tuesday, August 04, 2015 6:33 AM
To: SDW WG Public List
Subject: ISSUE 14: temporal reasoning and relations

Hello,

The oldest remaining issue with the UCR document is ISSUE-14<http://www.w3.org/2015/spatial/track/issues/14>: Not clear Time req. - temporal reasoning and relations (xsd formats). Until now the issue had no related e-mail thread. This message changes that. I hope we can all think about this issue and work towards resolving it - hopefully in next week's meeting.

My personal understanding is that this issue could be intended to lead to addition of a new requirement that is the temporal equivalent of the spatial operators requirement<http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#SpatialOperators>. Especially when considering inexact dates and times I think it would be good to have operators like 'before', 'after', 'during' at one's disposal. But when looking at the Time Ontology I see such concepts are already there. I understand them to be only usable with exact dates and times, but there already is a requirement for temporal vagueness<http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#TemporalVagueness>. Could this mean there is no reason to add another requirement?

Regards,
Frans


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Received on Wednesday, 5 August 2015 12:42:41 UTC

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