Re: Encoding an incomplete date as xsd:dateTime

There's already a slight problem in vCard's treatment of bday; it includes
 xsd:gYear, which is not permitted in OWL2-DL, and it does not include
xsd:string, which is available, and which is required by the RFC.

SPARQL 1.1 also does not support xsd:gYear - for example, the YEAR function
returns an integer.  You can work around the issue in SPARQL using STR, or
rely on local extensions.

OWL2-DL allows for facets on dataTime  to specify a minimum and maximum
time point value, which can be used in restrictions on individuals to yield
the appropriate models;  however, this approach is not ideal.

Pellet (and presumably Stardog)  handles non-DL xsd date types, albeit in a
slightly non-xsd standard way.

FACT++, JFact, and Hermit do not handle these types.

[Reasoning about named calendar years in terms of intervals bounded by time
points is painful, especially for years in the future.  Leap seconds can be
added with only about six months notice (
http://en.wikipedia.org/wiki/Leap_second ). Leap seconds are a PITA. ]

Simon


On Wed, Jun 25, 2014 at 10:42 AM, Jerven Bolleman <me@jerven.eu> wrote:

> Hi Bernard,
>
> Please do not go down the stuff everything in a single literal format
> that EDTF is. That is not a semweb solution that is a MARC solution.
> If that level of detail is really needed modeling it using the
> TimeOntology plus extra information for seasons etc.. is the correct
> way to go.
>
> Problems for EDTF is that OWL reasoners don't understand it. You can't
> SPARQL with it. And in general is just not appropriate in actually
> describing the time ranges.
> In other words I do not think this is appropriate for a standard
> ontology like vCard.
>
> Regards,
> Jerven
>
> On Wed, Jun 25, 2014 at 4:26 PM, Bernard Vatant
> <bernard.vatant@mondeca.com> wrote:
> > Hi all
> >
> > Are you aware of the Library of Congress Extended Date/Time Format
> (EDTF)?
> > There was an interesting presentation at DC 2013 about its
> implementation in
> > real world
> > http://dcevents.dublincore.org/IntConf/dc-2013/paper/view/183
> >
> > Bernard
> >
> >
> > 2014-06-25 16:00 GMT+02:00 Paul Houle <ontology2@gmail.com>:
> >
> >> I've been thinking about date representations a lot lately.  Even if
> >> you're going to cobble something together out of the various XSD
> >> types,  it still helps to have a theory.
> >>
> >> A better underlying data type for dates is a time interval or set of
> >> time intervals.
> >>
> >> This represents the fact that many "events" happen over a time
> >> interval (such as a meeting or movie show time),  that we often only
> >> know a year or a day,  that things are measured on idiosyncratic time
> >> basis such as the fiscal years of various organizations,  that there
> >> are both practical and theoretical limits on both the precision and
> >> accuracy of time measurements.
> >>
> >> Intervals have their charms,  but if you include interval sets you can
> >> also represent concepts such as "Monday", "June 25" and "the third
> >> Tuesday of the month".
> >>
> >> Of course,  it creates trouble that there is no total ordering over
> >> intervals/interval sets,  but that's a fundamental problem to any
> >> flexible time representation.
> >> ᐧ
> >>
> >> On Mon, Feb 10, 2014 at 9:37 AM, Heiko Paulheim
> >> <heiko@informatik.uni-mannheim.de> wrote:
> >> > Hi all,
> >> >
> >> > xsd:dateTime and xsd:date are used frequently for encoding dates in
> RDF,
> >> > e.g., for birthdays in the vcard ontology [1]. Is there any best
> >> > practice to
> >> > encode incomplete date information, e.g., if only the birth *year* of
> a
> >> > person is known?
> >> >
> >> > As far as I can see, the XSD spec enforces the provision of all date
> >> > components [2], but "1997-01-01" seems like a semantically wrong way
> of
> >> > expressing that someone is born in 1997, but the author does not know
> >> > exactly when.
> >> >
> >> > Thanks,
> >> > Heiko
> >> >
> >> > [1] http://www.w3.org/2006/vcard/ns
> >> > [2] http://www.w3.org/TR/xmlschema-2/#dateTime
> >> > [3] http://www.w3.org/TR/xmlschema-2/#date
> >> >
> >> > --
> >> > Dr. Heiko Paulheim
> >> > Research Group Data and Web Science
> >> > University of Mannheim
> >> > Phone: +49 621 181 2646
> >> > B6, 26, Room C1.08
> >> > D-68159 Mannheim
> >> >
> >> > Mail: heiko@informatik.uni-mannheim.de
> >> > Web: www.heikopaulheim.com
> >> >
> >> >
> >>
> >>
> >>
> >> --
> >> Paul Houle
> >> Expert on Freebase, DBpedia, Hadoop and RDF
> >> (607) 539 6254    paul.houle on Skype   ontology2@gmail.com
> >>
> >
> >
> >
> > --
> > Bernard Vatant
> > Vocabularies & Data Engineering
> > Tel :  + 33 (0)9 71 48 84 59
> > Skype : bernard.vatant
> > http://google.com/+BernardVatant
> > --------------------------------------------------------
> > Mondeca
> > 35 boulevard de Strasbourg 75010 Paris
> > www.mondeca.com
> > Follow us on Twitter : @mondecanews
> > ----------------------------------------------------------
>
>
>
> --
> Jerven Bolleman
> me@jerven.eu
>
>