Re: RSP Query Semantics - RDF Stream Processing Community Group

Hi all

That just didn¡¯t seem 100% clear to me.

best

Avi


On 04.04.2014, at 12:24, Jean Paul Calbimonte <jean-paul.calbimonte@epfl.ch> wrote:

> Thanks Avi, Roland,
> 
> Yes, intervals are taken into account in the model. If you see at the bottom of the page, we have been working also on (for example) the semantics of windows over an interval based graph stream. So, we are on the same train I think.
> 
> but of course we have to clean up the model a bit (there is more than one proposal right now).
> 
> Jean-Paul 
> 
> 
> > Date: Fri, 4 Apr 2014 10:51:53 +0200
> > From: mail@roland-stuehmer.de
> > To: bernstein@ifi.uzh.ch
> > CC: public-rsp@w3.org
> > Subject: Re: RSP Query Semantics - RDF Stream Processing Community Group
> > 
> > Abraham Bernstein wrote:
> > > A stream is a sequence (G, ¦Ó ) where ¦Ó ¡Ê T the set of all *intervals*.
> > >
> > > ¦Ó = [t_s, t_e], where t_s denotes the start time and t_e denotes the
> > > end time.
> > >
> > > As a short hand notation we could say that when t_s = t_e then one can
> > > only write one of them.
> > 
> > +1 for Intervals and +1 for the short notation (defaulting to time points)!
> > 
> > Darko and I are using intervals internally because it fixes problems
> > with instantaneous occurrences in complex event, see [1].
> > 
> > Contrary to an intuitive understanding the expressions E1->(E2->E3) and
> > E2->(E1->E3) ("->" is "followed by") are equal with point-based
> > semantics. The order of the events E1 and E2 in the example is
> > inconsequential because the whole event is detected if the event in
> > before the parentheses is detected before E3. No relation between events
> > in position one and two is specified. Both expressions are fulfilled by
> > the same event histories: e1,e2,e3 and e2,e1,e3.
> > 
> > This is not expected from the "followed by" relation. Interval-based
> > semantics solves these problems by viewing complex events as occurring
> > over the interval from the occurrence of the first constituent event,
> > the initiator, to the end of the last constituent event, the terminator.
> > 
> > Best!
> > 
> > Roland.
> > 
> > [1] Section 4 "Why Detection Conditions are Inadequate" of
> > http://users.ecs.soton.ac.uk/jca/dexa2002.pdf
> > Galton, A. & Augusto, J. C. (2002), Two Approaches to Event Definition,
> > in 'DEXA '02:
> > 

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|  University of Z¨¹rich, Department of Informatics
|  web: http://www.ifi.uzh.ch/ddis/bernstein.html