[Top] [All Lists]

Re: [ontolog-forum] Foundation Ontology Primitives

To: Patrick Cassidy <pat@xxxxxxxxx>
Cc: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>, ian@xxxxxxxxxxxxxxxx
From: Pat Hayes <phayes@xxxxxxx>
Date: Thu, 4 Feb 2010 23:03:28 -0600
Message-id: <913A1675-2C41-433A-B4E6-45B4CA869B6D@xxxxxxx>

On Feb 2, 2010, at 12:50 PM, Patrick Cassidy wrote:    (01)

> Ian,
>   Good to hear from you, I have never had a reason to filter your  
> posting.
>   Reasonable questions, and I will try to answer interspersed below.
>> In the thread that's been running, you indicate that you believe  
>> there
>> are some common ontic primitives that can be shared across multiple
>> ontologies -
>> e.g. as a foundation. Do you have a clear idea of what these might  
>> be ?
>> (some examples would really help my understanding).
>   I don't have a comprehensive list, but I have been taking the  
> Longman
> defining vocabulary (2148 words) as an initial approximation, and  
> trying to
> represent those concepts (possibly more than one per word) in the  
> ontology, together with other concepts required to describe and  
> reason with
> those.  Among the most basic concepts are really abstract things  
> like object
> and attribute and event, too primitive to logically define, and  
> represented
> only by the relations among them - and comprehensible to people  
> mostly by
> reference to examples.  I would consider "Mass" as primitive - in  
> that case,
> a "PhysicalObject" (as defined in COSMO) would not be a primitive  
> because it
> can be necessarily defined as an Object that has Mass; nevertheless,  
> it
> would be hard to have a perspicuous FO without the notion of  
> PhysicalObject.
> I have over 7000 classes (types)in the ontology, but many of those are
> probably not primitive, they are only included to make it easier to  
> create a
> natural language interface to the FO.  So at this point I haven't  
> tried to
> tease out the true primitives from decomposable concept  
> representations.
> Pat Hayes has mentioned that all of his time theories can be  
> "expressed by"
> (Pat Hayes's phrase) axioms containing only three classes, time  
> point, time
> interval, and duration, plus some relations among them.   Those  
> three are
> among the concepts I would consider as primitive    (02)

But Pat, look, there aren't three concepts here. There are 3N, where N  
is the number of distinct (mutually incompatible) theories. I havent  
checked recently, but N is at least 10 in my old survey, which you are  
citing here.  Interval in a theory of a continuous timeline, and  
interval in a theory of reversible intervals in the glass continuum,  
are very different ideas. They satisfy different axioms.    (03)

> , and the different time
> theories that can be expressed using those common concepts may be  
> logically
> incompatible    (04)

No no NO. You are saying this wrong, and your version is a  
hallucination. There are not three concepts with a variety of theories  
expressing them. Each theory nails down ONE set of concepts. And they  
are ALL 'primitive' in that theory, and they are not primitive or non- 
primitive in any other theory, because they aren't in any other theory  
AT ALL.    (05)

> , but they can be represented as theories and not as part of the
> basic ontological commitment of the FO itself.  (PatH may not agree  
> with
> this terminology).    (06)

Damn right. There is no FO for my 'time catalog'. That is why its  
stated as a catalog of temporal theorIES. If I could have found a  
single primitive theory I would have written it down. But I couldnt  
find one.    (07)

>  There is no logical contradiction in an ontology
> *describing* logically contradictory theories    (08)

Yes, there is, at least if an ontology is itself a logical theory,  
which I take it we all agree that it is.    (09)

> - a contradiction would occur
> only if the theories were all asserted to be true.  So the  
> primitives are
> those things that we use to describe all the things about which we may
> disagree.
> Numbers would be primitives, and some other mathematical concepts.   
> So would
> the concepts related to physical space such as spatial interval  
> (interpreted
> in a single motion frame and independent of relativity), and those  
> can be
> linked to more abstract notions of space without rendering the  
> physical
> space as decomposable, because there are aspects of physical space  
> that are
> not susceptible to complete definition.  Many things that we can  
> directly
> perceive would be primitives, such as "force"; there are things we  
> can say
> about force other than F=ma.  I think that even "person" may be  
> primitive
> (though "animal" may not be).  I think that "Light" (the form of
> electromagnetic radiation) would also be primitive The actual list  
> would
> have to be determined by seeing what set of concept representations
> ultimately serves to create the preferred ontology elements for a  
> fairly
> large group of users.
> I hope that it will not actually be necessary to try to precisely  
> define
> the borderline between primitive and non-primitive.    (010)

There is no border between these at all. Or at any rate, if you think  
this distinction is meaningful, you will have to seek for its meaning  
outside the confines of any semantic formalism I know about. In  
logical axioms, all nonlogical names are equally 'primitive', and all  
of their meanings depend upon all the others; except in the rare cases  
where one of them is definitionally eliminable, which of course is not  
going to happen for any concepts outside of mathematics.    (011)

>  My point was that we
> should include all of the primitives in the FO, but useful basic  
> concepts,
> even if they are *not* primitive, could be very helpful in the FO  
> unless
> they proved to be controversial, at which point it would be  
> necessary to
> make any distinctions that the users feel are important.  The most  
> important
> criterion is, if some domain needs a concept representation, and it  
> cannot
> be expressed logically (to the satisfaction of the user) as some  
> combination
> of existing ontology elements, then it would probably have to be  
> included as
> a new primitive.  My expectation is that, after some initial period  
> in which
> the FO is used by, say, at least 50 independent groups, the need to  
> add new
> primitives will dwindle    (012)

I see no reason why the rate would dip even slightly. Cyc did not  
experience any such 'reduction to the primitive'.    (013)

> to at most a few per year - it may never go
> completely to zero.  That level of stability would, I expect,  
> provide the
> required basis for accurate interoperability.
> [IB] > > If I have an issue with this idea, it is one of pragmatism.  
> As an
>> aspiration, a common foundation ontology is something I would really
>> support. There seems to me to be a couple of practical problems:
>> * Reaching consensus - ontology is a topic that attracts people with
>> strong opinions. Consensus requires compromise, and I don't see  
>> much of
> that
>> going on in this community. In my experience of developing ISO  
>> standards,
> it
>> usually requires a commercial reward to ensure true consensus is  
>> met -
>> i.e. they all (well, most) stop bickering if they can see some
> profitability
>> in not bickering. I don't think ontology is at the maturity level  
>> where
>> huge  sums of money depend on its success or failure, so I fear  
>> consensus
> is
>> going to be nigh impossible.
>  That is the primary problem, but I think the difficulty has been  
> greatly
> overestimated.  Your point about *motivation* is, I believe,  
> precisely the
> key to the solution.    (014)

It is a key point. What bothers me most about your ideas is not that  
they won't work. They won't, but still the effort might be worth  
trying. But it is the experience with attempts that have already been  
made in this general direction. The OBO foundry, for example, is in  
wide use, has funding, a vibrant and active user community, etc..  But  
it embodies and sets in stone some very bad (IMO) ontological  
decisions. And now it is impossible to change or even discuss these  
because the very utility of the 'consensus' of the OBO foundation  
makes it practically impossible to change it. The same thing happened  
with RDF and HTML: casual early decisions made on a temporary basis  
became almost impossible to undo because so much was invested in them.  
People are talking about a revision to RDF, but others have pointed  
out that even small changes now would cost millions of dollars to get  
to adoption.    (015)

This kind of ossification of early decisions happens throughout large- 
scale standards activities, and I see no reason why it won't happen  
here in the same way and for the same reasons. We will finish up with  
a poor ontology, built using poor justifications, but heavily invested  
so highly resistant to change. Which is exactly what we have already  
in many areas. What you need is not a revolution in ontology  
engineering, but a revolution is large-scale intellectual management,  
and I havn't seen anything along those lines in your proposals.  Any  
group larger than about 15 people will not converge on a single  
product in any reasonable timescale.    (016)

Pat Hayes    (017)

Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/  
Config Subscr: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/  
Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files: http://ontolog.cim3.net/file/
Community Wiki: http://ontolog.cim3.net/wiki/ 
To join: http://ontolog.cim3.net/cgi-bin/wiki.pl?WikiHomePage#nid1J
To Post: mailto:ontolog-forum@xxxxxxxxxxxxxxxx    (018)

<Prev in Thread] Current Thread [Next in Thread>