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Subject: Re: [legalruleml] Time Instants or Time Points

Thanks Adrian.

In legal applications, it appears to me that both discrete and continuous of timescales are needed. When describing an observation of the time at which a physical event takes place (e.g. publication), then a discrete timescale is appropriate because this captures the fact that all observations have limited precision. Discrete timescales capture this uncertainty as intervals in time in a similar way that significant digits are used to record numerical measurements in general, (except that the time interval is assumed to lie on the future side of the time observation rather than being centered on the measurement as is done with significant digits.)

When defining a fiat event (e.g start of enforceability), then a continuous timescale may be appropriate because the definition can be made with infinite precision.

I have included the <ruleml:Time> element in the LegalRuleML schema, but so far I have only implement a restricted content model of the form

<ruleml:Time><ruleml:Data xsi:type="xs:dateTime>2012-10-02T10:45:34-00:00</ruleml:Data></ruleml:Time>

I have a couple of questions:

1. Based on what you say below, the interpretation of this construct appears to be ambiguous because there is no @type on the Time element.

If a discrete timescale is adopted, this would represent an interval of length one second.

If a continuous timescale is adopted, this would be interpreted as a time instant, in particular the beginning of the time interval described by
<ruleml:Data xsi:type="xs:dateTime>2012-10-02T10:45:34-00:00</ruleml:Data>

Is there a default selection between continuous and discrete timescale that would resolve this ambiguity?

Since the argument
<ruleml:Data xsi:type="xs:dateTime>2012-10-02T10:45:34-00:00</ruleml:Data>
already denotes a temporal entity, a time period of length 1 second (the value space of xs:dateTime is actual time periods and is based on ISO 8601), I would expect the default, if there is one, to be the discrete timescale.

2. I would like to include more of the content model for this element as defined in the Reaction RuleML schema

but the interpretation of this more general syntax is not clear to me.
According to the schema, the content model appears to be essentially unrestricted:

Is it possible to use the element <ruleml:Time> to describe a timepoint that is 6 months after some named timepoint?
( <ruleml:Time key="#t1">...</ruleml:Time> )


On 10/20/2012 9:24 AM, Adrian Paschke wrote:
Hi Tara,

Yes, there are many existing ontologies and vocabularies/schemas available for time. Since there is nothing special about the representation of time in the legal domain which would require a domain-specific model, we should reuse them.

Reaction RuleML therefore has a generic approach which supports this reuse. There is a basic distinction in whether the temporal aspect are based on the relationships between "time instants" (type="ruleml:TimeInstant") or "time intervals" (type="ruleml:TimeInterval">). Depending on this core distinction a time becomes a linear continuous time model with points in time called "time instants"(<Time type="ruleml:TimeInstant">) or a discrete time interval model with "time points" (<Time type="ruleml:TimePoint">) as a relative time interval with an absolute reference or a relative reference to some given time interval.

A duration is an amounts of time, .e.g. <ruleml:Time> <ruleml:Data xsi:type="xs:duration">P5Y2M10D</ruleml:Data> </ruleml:Time> or other quantities of duration values with other types of time units including nominal time units, e.g.3 years  <ruleml:Time><Ind iri="owl-time:Year">3</Ind><ruleml:Time> and discrete time functions (<ruleML:Time><Expr>).

<Interval> in Reaction RuleML is a generic concept for modeling intervals (Time/Spatial/Event/Action/Situation Intervals). Time intervals are then either based on the  segments of a linear continuum of time instants or the discrete time points (which span a smaller time interval).

Reaction RuleML also has a rich set of algebra operators for intervals (Allens relations such as During, Overlaps, ...) and general time arithmetic's and aggregators (such as Every, Timer, Any, ...-), and a general <Operator> (XML extension point) for adding further special operators from the many existing domain specific languages.

So, depending on whether the Legal RuleML collection is a set of time points it would be <lrml:TimePoints>  or <lrml:TimeInstants> in the case of time instants.
I would propose to be more generic and say <lrml:Collection type="ruleml:TimePoint">, so that we can have different types of Collections.


From: legalruleml@lists.oasis-open.org [mailto:legalruleml@lists.oasis-open.org] On Behalf Of Tara Athan
Sent: Donnerstag, 18. Oktober 2012 01:02
To: legalruleml@lists.oasis-open.org
Subject: [legalruleml] Time Instants or Time Points

There is a relatively recent date-time ontology published by OMG (http://www.nist.gov/customcf/get_pdf.cfm?pub_id=911074) that addresses time scale granularity and also solves the problem of duration (is 1 month greater, equal or less than 30 days?)

While LegalRuleML is not supposed to be dependent on any particular ontology, this work does provide a useful conceptualization that allows certain intervals of time to be specified with a single datum. For example the date 2012-10-12 corresponds to a particular interval of time which can be specialized to a particular 24 hr interval when a timezone is added. This general concept of a point on a time scale with a particular granularity is called "time point". It is more general than a "point in time" or "time instant", but could include that concept if the time scale is continuous.

I proposed that we adopt this terminology, (but not the ontology) by referring to a collection of <ruleml:Time> elements as <lrml:TimePoints>

This also avoids the unfortunate plural "Times", which could be confused with multiplication or repitition, while retaining generality regarding the granularity, if any, of the time scale.


   <ruleml:Time key="t1"> <ruleml:Data xsi:type="xs:dateTime">2012-07-21T00:00:00Z</ruleml:Data> </ruleml:Time>
   <ruleml:Time key="t2"> <ruleml:Data xsi:type="xs:date">2012-07-21</ruleml:Data> </ruleml:Time> </lrml:TimePoints>


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