Chris, Matthew,
You have both expressed the point I was making better than I did, and I
agree with your comments. Even so, I can't resist trying to summarize again
by first reiterating the starting point for this thread about meaning. ( the
emails from ChrisP and MatthewW are included below my signature for
reference if needed):
(1) In order to support general accurate semantic interoperability the
Foundation Ontology should be as stable as possible. That is why I think an
effort to identify as many as possible of the semantic primitives should be
one priority of the early phase, to minimize the need for subsequent changes
to the FO.
(2) PatH and JohnS have pointed out that the "meanings" accessible to the
computer's reasoning mechanism are the total sum of all inferences, which
change in some way (perhaps only by addition) when any change is made to the
ontology. No disagreement.
(3) But recognizing that the goal of the FO is to support the purposes of
the programmers and ontologists who use it in applications, it is the
*intended meanings* of the ontology elements that are of primary importance,
because they determine what goes into the ontology. The users are not at
the mercy of any unintended inference that, willy-nilly, may pop up when a
change is made to the ontology; if the behavior of the programs using the
ontology shows that the meanings accessible to the computer that affect
program behavior have changed in some *undesirable* way, then that change to
the ontology must be rescinded or additional modifications made to bring the
behavior of the programs back to that desired. It is the intended meanings
of the ontology elements that determines what inferences will be made by the
ontology, not vice-versa, because the ontologist is in control of both. The
intended meanings *can* and *should* be stable, and the ontology should
express those intended meanings.
So saying that the intended meanings of the ontology elements should be
stable, and also saying that the computer only knows the meanings supported
by the logic of the ontology, are not contradictory. The logical inferences
are critical in determining what the computer can do with an ontology, but
the intended meanings of the ontology elements constrain what can go into
the ontology - and therefore what inferences will be made. For the FO
approach to interoperability, I think that fixing the intended meanings of
the primitives will be a high priority. It is desirable to formalize those
intended meanings as precisely as possible, but there may still be
references to instances and other documentation, not formally reflected in
the ontology structure, that help the ontologist and programmer to avoid
making changes that cause unintended and undesirable consequences in
programs. (01)
And of course we cannot expect perfection from this strategy, but I think we
will get *closer* to general accurate interoperability by this tactic than
by just mapping domain ontologies to each other. I also expect FO-base
interoperability to be faster and cheaper than alternatives. (02)
Pat (03)
Patrick Cassidy
MICRA, Inc.
908-561-3416
cell: 908-565-4053
cassidy@xxxxxxxxx (04)
============================================================= (05)
[[From Matthew West]]
Dear PatH and PatC, (06)
Let me have a go at this. (07)
> > The disconnect between PatH's view of "meaning" and mine is that
> > he is content to believe that the meanings of the elements used in
> programs,
> > databases, ontologies (e.g. time, distance, physical object, dollar,
> > person)
> > all change every time we add a new assertion about unicorns, and I
> > am not.
>
> It is not a matter of being content to believe. I am asserting this AS
> A FACT, and you are simply in denial about elementary facts of
> semantic theory. Now, of course, you are free to invent an alternative
> semantic theory, one that supports your intuitions about meanings
> being fixed when axioms change, but I would like to see that theory
> given some reasonably precise flesh before proceeding to discuss this
> matter very much further. (08)
MW: I suspect the real problem here is that you are each looking through
opposite ends of the telescope. Let me describe the different views: (09)
PatH looks at it from the theory end, and says that when you change an axiom
in a theory there is a different set of models that it picks out. Absolutely
right. It "means" something different. (010)
PatC looks at it from the other end. He has a particular intended
interpretation, and his question is: if he changes this axiom does it still
pick out his intended interpretation (he doesn't care about any unintended
interpretations). If it does, as far as he is concerned it "means" the same
thing. Also true. (011)
I think there is something to be accommodated from both sides here in
practical ontology development (012)
Regards (013)
Matthew West
Information Junction
Tel: +44 560 302 3685
Mobile: +44 750 3385279
matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
http://www.informationjunction.co.uk/
http://www.matthew-west.org.uk/ (014)
==========================================
[[From Chris Partridge]] (015)
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> bounces@xxxxxxxxxxxxxxxx] On Behalf Of Chris Partridge
> Sent: Tuesday, March 02, 2010 4:24 AM
> To: '[ontolog-forum] '
> Subject: Re: [ontolog-forum] Foundation ontology, CYC, and Mapping
>
> Pat,
>
> I agree that it is a common fallacy to somehow assume that the computer
> can
> read our intentions - and it is important to check we are not making it
> (and
> to point it out when we see it).
> And that the formal ontology we give the computer has a formal
> semantics
> that may constrain the intended interpretation, but does not (and is
> not
> intended to) capture it.
>
> My intention was to make (in a sense) the inverse point - that when we
> build
> an ontology it is a similar fallacy to say we are only interested in
> the
> formal semantics. (Does anyone on the list think this is not a fallacy?
> I
> have met people who do.)
>
> (To reiterate your buggy software point below a little more prosaically,
> but
> hopefully accurately.) When we construct the ontology we have an
> intended
> interpretation - if we are building a financial ontology when we add
> axioms
> about equities, we have an intended interpretation for 'equities' and
> we
> judge whether the axioms make sense in terms of this interpretation.
> Similarly, when we deploy the ontology, we use it to work with the
> intended
> interpretation - we would not normally deploy the financial ontology in,
> say, an offshore oil processing system and interpret 'equities' as oil
> rigs.
>
> So, clearly, without an intended interpretation, the ontology is of no
> practical use.
>
> This seems to me to imply that when we are thinking about the process
> of
> developing an ontology, it is useful to have some way of talking about
> and
> sharing this intended interpretation. In the scenario you describe
> below,
> where you are the (only) person writing the program then " My intended
> behavior is quite clear", but in larger teams and where external QA is
> required - more of a framework is needed. So the 'intended
> interpretation'
> can be practically formalised the better - it is not a good strategy to
> dismiss it as subjective and irrelevant. (The notion of intended
> interpretation is a good starting point.)
>
> I suspect this is partly why PatC (and others) make some of the points
> they
> do (PatC, feel free to tell me I am mistaken).
>
> If one can agree an intended interpretation for a FO (or some high
> level
> elements of one) then this is inherited by the sub-types - so it is a
> cost-effective mechanism for tying down the interpretation. (As an
> aside, my
> gut feeling is that PatC's strategy for doing this is not going to bear
> fruit - but it is good research to explore the options.)
> At the lower level, if one can agree the intended interpretation for
> some
> terms with a high degree of certainty (which may require some work) -
> then
> this is independent of the theory/ontology the terms are embedded in
> and is
> portable across them.
>
> Where this works well is with proper names (especially if you assume a
> direct reference theory (an intended interpretation?)).
> It works less well where the terms (in the wild) come with
> connation/sense.
>
> I think some of the feeling expressed in earlier posts that high level
> terms
> (such as set) can be ported across theories with contradictory axioms
> arise
> from (mistakenly) assuming they have simply portable intended
> interpretations.
> That does not mean that other terms are not simply portable or that we
> do
> not need to work with intended interpretations. Indeed, given that the
> practical value of ontologies arises from the intended interpretations,
> in
> many situations when producing ontologies these may be key and the
> formal
> semantics merely a supporting mechanism.
>
> Regards,
> Chris
> (016)
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