roy at cacr.caltech.edu
Tue Jun 14 08:47:54 PDT 2005
On Jun 14, 2005, at 12:47 AM, Frederic V. "Rick" Hessman wrote:
> I think we'd all appreciate a general comment on whether ucd-sci is
> the right place for a discussion
> of what we have tenatively called VOConcept.
It says in the UCD document "UCD describe astronomical quantities",
meaning that they are "semantic meaning of data quantities", for
example "phys.temperature". The implication is that UCD is NOT
something like "satellite.Phobos;planet.Mars" and it is NOT something
like "image.jpeg;human.JacquesChirac". I believe that the scope here is
correct, and that extensions in to these other areas of knowledge will
slow down the well-developed and sophisticated UCD effort. One of the
best things about UCD is that it has been mined from thousands of table
instances written by hundreds of astronomers, and therefore has
unimpeachable credentials as a representation of the astronomical
However, we should tackle wider questions when supported by use cases
from the community. I believe the UCD effort should become part of a
wider "semantics" effort, which may use UCD syntax for other areas of
knowledge (eg. astrophysical events), or it may use OWL or RDF or other
syntax. Frankly I don't care about the syntax part, that comes later:
what is important in these semantics efforts is formalizing some branch
of knowledge so that computers can record, compare, and deduce.
> Yes, there are lots of potential relations between VOConcept and UCD
I would prefer not to use the term "VOConcept", as it is too vague. I
think the Semantics WG should concentrate on small, well-defined,
> You might ask us to please shut up and worry about this later, but
> we're in the final throes of finishing VOEvent 1.0 and need to make a
> short-term decision about whether we ignore the problem of naming for
> now (at the cost of a loss of naming capability) or make an initial
> plunge in the direction of a UCD-like VOConcept (whatever you want to
> call it).
I think that VOEvent should be published as version 1.0 Working Draft
without any formal semantics for describing events, but rather describe
events in natural language: "Looks like an exploding square galaxy"
would be a typical description. Then in VOEvent 1.1 we can tackle
formal semantics and other matters.
And that formal description of astronomical events should not be called
"VOConcept", but something more specific, such as "Unified Event
Description", or "VOEventDescription". The first task of that
discussion group is define what is the area of knowledge that is being
covered, and agree to a short paragraph expressing what is an is not
being formalized into syntax. For example, in VOEventDescription, is it
an event when Michael Jackson is acquitted? How about when a new planet
is discovered? How about a flare from a star that flares every 2 weeks?
I believe that defining scope is the key to progress here, and that the
tighter that scope, the better chances for agreement. Otherwise we are
caught in a morass of ontological questions. In the words of Bill
Clinton, "It depends upon what the meaning of the word is means. "
> Please vote:
> ___ Please stop talking about VOConcept in this list - we have enough
> to worry about as it is.
> ___ I think the two issues are still related enough to warrant
> inclusion in the ucd-sci discussion list for now.
> Based upon the tally, we can decide to continue (at least now and
> then) or to start a new list.
I think the discussion of VOEventDescription should take place in the
VOEvent mailing list, perhaps copying the entire Semantics WG when
wider issues come up.
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