Fwd: some remarks on VOEvent

[Rob Seaman]

On Jun 4, 2005, at 7:13 AM, Ed Shaya wrote:

>   I'm afraid I don't get what you are flaming about here.  Why is  
> it possible to define a VOEvent but not an event?

My apologies if I seemed to be flaming.  I thought we were just  
having a conversation - expressing diverse views.

A VOEvent - as Roy helpfully pointed out - is the report of an  
observation.  Hundreds of years of scientific developments have  
provided very fine grained utilitarian definitions of "observation"  
and "measurement" and other experimental concepts - and of specific  
flavor reports of same.  "Event" is a nice flexible English word -  
but more on the theoretical side than the experimental.  In its  
colloquial sense, the word "event" is likely broader in its  
connotations in astronomy than in any other discipline.  I thought  
the point of ontology was precisely to capture colloquial meanings in  
a bottle.  I suspect "event" is one such word that will be hard to so  
capture.  My worry - a worry that I've heard others express without  
deeming them to be flaming - is that "ontology" is a synonym for "non- 
pragmatic".

> Ontology allows one to use natural language to make statements and  
> query.  The whole idea is to bring the flexibility of human  
> language to machines (but perhaps to make it a bit clearer).  If  
> you think this is a vain hope then why are you on this list?

I don't think it is a vain hope to build targeted ontologies - note  
the plural.  I'm on the list because all of a sudden there are four  
or more lists for discussing VO semantics and we keep being shuffled  
off to the next list over.  VOEvent presents an interesting  
opportunity for the VO to wrestle with real world semantic  
requirements.  Should this particular list be renamed  
"ontology at ivoa.net"?  Can semantics be profitably pursued as an  
activity separate from other VO work?

> Ah.  So what you want is inflexibility.  You want to ensure that  
> VOEvents do not have explanations of explanations or any other deep  
> discussion of the event.

Not what I want at all.  Although I might suggest that "deep  
discussion" is an emergent property from a long sequence of richly  
braided followup packets.  To optimize its utility, a single VOEvent  
will typically express a single coherent observation or hypothesis.   
VOEvent is a specific VO facility with a clear mission - to report  
alerts to the community via software agents.  In many instances,  
VOEvents will be used to trigger more in depth analysis via other VO  
facilities.  An "alert" and a "deep discussion" are indeed quite  
different modes of communication.

> If the VO wants hardwired structures it should study the issue with  
> Ontologies (because only in ontologies can you see the big picture  
> with relationships between all of the components of the langauge)   
> and then use that as a starting point for creating limiting UML or  
> Schema.

"Limiting UML"?  :-)  If an ontology is something so open-ended that  
UML is seen to be limited by comparison, then perhaps Merriam-Webster  
is right to call ontology a branch of metaphysics.  I was just  
standing up for ontologies the other day on one of the gazillions of  
UCD lists.  There is little point to UCDs without an underlying  
ontological formalism.  But by the same token, there is little point  
to ontologies if they aren't seen to be pragmatically wrestling with  
real world issues - at least on occasion.  VOEvent is an opportunity  
for elucidating real world requirements and building real world VO  
systems.

Phenomenologically yours,

Rob


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