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000013_ahn@cbnmva.att.com _Wed Sep 15 07:02:23 1993.msg
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Received: from univers.CS.Arizona.EDU by optima.CS.Arizona.EDU (5.65c/15) via SMTP
id AA03929; Wed, 15 Sep 1993 07:02:24 MST
Date: Wed, 15 Sep 1993 07:02:23 MST
From: ahn@cbnmva.att.com
Message-Id: <199309151402.AA04943@univers.cs.arizona.edu>
Received: from att.UUCP by univers.cs.arizona.edu; Wed, 15 Sep 1993 07:02:23 MST
To: gadia@cs.iastate.edu
Cc: tdbglossary@cs.arizona.edu
Subject: Re: Ahn's message on temporal element
From: Shashi K. Gadia <gadia@cs.iastate.edu>
Subject: Ahn's message on temporal element
To: ahn@cbnmva.att.com
Date: Tue, 14 Sep 93 14:36:17 CDT
A temporal element in one dimension is
a union but NOT a set of intervals.
Greetings.
If a union is a set operator, doesn't a union of intervals
result in a set (of intervals) ?
I don't see the significance of the distinction here.
The terms "Multi-intervals" or "Interval sets"
or simply "Intervals" lean towards a set and
not union.
I don't see how "temporal element" denotes a union better,
if a distinction between a set and a union is important.
The term temporal element is more generic.
In the bitemporal model, it is union of rectangles.
Moreover if your bitemporal space does not contain
notion of future the bitemporal space reduces
to triangle below the diagonal. And a temporal
element becomes union of triangles and rectangles.
(See Section 6.2 on page P-26 of workshop
proceedings.)
Term "interval" is used in a general sense too.
For example, Section 3.15 mentions bitemporal intervals.
The term temporal element generalizes to spatial
or spatio-temporal element. A spatio temporal
element can be very complex.
A temporal element reminds me of a picture element, which is a pixel.
This unintended similarity may become more significant
in a spatio-temporal DB which may deal with images.
Regards
Ilsoo Ahn