Re: Examples of Syntax and semantics

Henry,
Thank you for the useful reply.
But I don't think this deals with the issues of mediation between two
similar but semantically disjoint ontologies.
You have said that how a mapping of one into another is done is important,
but how might it be done? I imagine this would be a role for the
establishment of more abstract principals, presumably the field of UFOs?

> There are an infinite number of relations between things.  You can
> define the relations you wish. But if they are not useful they will
> just be laying around unused.
>
There are an infinite number of relationships between things.
This is why I think one notion of the semweb is futile and misguided, that
vision of uniting huge tranches of the current documents on the web in some
ubber tagged universe.
One may home in on some area and describe and re-describe it to any level of
detail and for many different purposes. Theoretically there could always be
another re-description, as yet unmade, that would be more useful than the
last.
I had thought that part of the definition of the SemWeb was that there was
some public de facto language used for that description. Thus, while a
description may be made public, the language would be public so that anyone
with the correct authority could add to or edit that description (by
description I mean e.g. an OWL description of the relationship between
different elements in the subject). Moreover the document could readily and
variously be made public if so desired.
But if they are not useful they will
just be laying around unused.
This is a tautology. It is not a sufficient definition of "useful".
What is useful. You have intimated what is used most. But I may not care. I
may think useful is what makes me most money (maybe a small, high value
niche), while you may think that is completely useless.
This picture is not so problematic, but I think the corollary is, which is
it may be possible to purchase the usefulness i.e. the wider acceptance, of
an ontological description.
There is a huge difference between sponsoring a technical solution by
pumping money into research as, Microsoft does, only to have this matched by
an alternative created by SUN and merely sponsoring an ontology for brand
awareness purposes, but it seems to me that an ontology could be subverted
to the latter aim. This so easily could have been the case with foaf had it
been invented by a single company. This seems all the more dangerous if the
criteria for usefulness and, therefore, whether it survives, is the amount
it is used rather than paying attention to more general principals of
design.
Adam
On 05/04/06, Henry Story <henry.story@bblfish.net> wrote:
>
>
> On 5 Apr 2006, at 15:37, adasal wrote:
> > Henry,
> > It seems rather late in the day to be defining the diference
> > between syntax and semantics, with regard to which imagine the
> > following.
> > A painting is fully described in mathematical terms. You can go to
> > any level of complexity, devise any scheme you like to describe the
> > texture of the paint, the juxtaposition of colours, what you will
> > to *completely* describe it, but the language and its syntax is so
> > at odds to that of painting you will not be able to convey the
> > meaning of the painting to another human in this way.
> > So it is, less dramatically, between one ontology and another
> > although ostensibly about the same subject. Without an underlying
> > framework what are such ontologies predicated on? Trial and error
> > in the popularity stakes?
>
> Yes. Natural selection is the final arbitrer. Though others like to
> refer to it is as God.  Since you like quoting philosophy books you
> may want to check out Ruth Garrett Millikan's "Language, Thought, and
> Other Biological Categories: New Foundations for Realism" [1]
>
> > You said:-
> > < http://xmlns.com/foaf/0.1/Person> (Let's abbreviate that to
> > foaf:Person from here on) always refers to the class of persons.
> > foaf:knows always to the same relation between persons.
> >
> > And I understand that the point is that the a foaf person in
> > defined is available to all at the URL.
> > But the problem comes when I want to redefine that which would
> > manifest in either extending http://xmlns.com/foaf/0.1/Person or
> > by my own definition http://xmlns.com/asaltieldeffoaf/0.1/Person
> > or, worse, where there is an implicit change. In fact this has
> > happened in foaf:knows since the way this is used entails a very
> > attenuated sense of "knows" due to foaf based programs (e.g.
> > LinkedIn). One certainly cannot rely on foaf:knows in the way that
> > one ordinarily uses the term "I know June and I know Justin."
>
> foaf:knows is defined at the url http://xmlns.com/foaf/0.1/knows. It
> is explicity not the general term knows
> such as defined by Nozick in Philosophical Investigations
>
>         S knows p iff
>                 p
>                 S believes p
>                 if p were false S would not believe p
>                 if p were true S would believe p
>
> Since for one the foaf:knows relation relates 2 people.
>
> There are an infinite number of relations between things.  You can
> define the relations you wish. But if they are not useful they will
> just be laying around unused.
>
> > (And notice the shades of meaning that can be attached to "I know
> > June" or, again, "I know June and Justin.")
>
> foaf:knows is a specialization of those usages of 'knows'. It need
> not be equivalent. It need just be useful.
>
> > So I may wish intenstionally to adjust foaf to accommodate some of
> > these shades of meaning.
> > I then may mistakenly think that I can normalize http://xmlns.com/
> > asaltieldeffoaf/0.1/Person to http://xmlns.com/foaf/0.1/Person
>
> Perhaps you would better buy your own domain name adasal.info and
> then you would put your new ontology
> at http://adasal.info/foaf/0.1/
>
> The point is that because the URLs used to name the things are also
> closely related to the name of the document where
> these can be found, it is both easy to find the meanings of the
> names, and also difficult to override the meaning of the legitimate
> owner.
>
> > by mapping some essential property of my definition of knows to
> > foaf:knows and leaving the other properties as (? I don't know the
> > technical details but I will imagine this) anonymous properties in
> > foaf effectively extending foaf to my own purpose but in an
> > unsatisfactory way.
>
> How you do that will be important. You could do it badly and end up
> with an empty class. Or you could end up with something that worked
> differently than what you think.
>
> > What would have happened at this point is that my original meaning
> > would be lost, this is because foaf:knows has its own meaning, due
> > to usage as much as anything, and my sense of asaltieldeffoaf:knows
> > such as knows as good friend, knows as in the brief acquaintance of
> > a collegue and so on, would not fit into foaf:knows.
>
> ok so you want adasal:goodFriendknows . Just put the following into a
> file http://adasal.info/foaf/ontology.owl
>
> adasal:goodFriendKnows rdfs:subPropertyOf foaf:knows;
>                         rdfs:subPropertyOf adasal:friend;
>                 rdfs:comment "a specialised way of knowing between people
> that are
> good friends" .
>
> you could also do this as an N3 rule
>
> { ?p adasal:goodFriendKnows ?f } => { ?p foaf:knows ?f;
> adasal:friend ?f . } .
>
> > You said:-
> > The trick is that the names you use (URIs) from one language to the
> > other are always the same. The semantics is captured in the
> > relationship between the names and the things (which is what
> > semantics is about).
>
> Does the above help?
>
> > So how would this work in the example I have given?
> > Best,
> > Adam
>
>
> [1] http://www.amazon.com/gp/product/0262631156/qid=1144244641/sr=1-1/
> ref=sr_1_1/103-6405064-4716631?s=books&v=glance&n=283155
>
>