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Re: [ontac-forum] Re: Semantic Layers (Was Interpretation of RDFreificat

To: "ONTAC-WG General Discussion" <ontac-forum@xxxxxxxxxxxxxx>
From: "Danny Ayers" <danny.ayers@xxxxxxxxx>
Date: Mon, 3 Apr 2006 18:03:05 +0200
Message-id: <1f2ed5cd0604030903h4cd7f39exbe7af277f2f4d04d@xxxxxxxxxxxxxx>
On 4/3/06, Azamat <abdoul@xxxxxxxxxxxxxx> wrote:
> Danny,
> One problem maybe, as you recognize yourself: ''I'm neither a philosopher
> nor logician" nor an ontologist,    (01)

Ok, but I know on which lists to lurk ;-)    (02)

> Another problem, more serious, any of the SW formal logical languages tells
> about the ontological nature of its polar constructs: individual, class, and
> property; their basic meanings, kinds, relationships, and instances, see
> USECS, for example. So those langauges are good rather for killing the web
> applications instead of building the killer apps.    (03)

I'm sorry, but the majority of web applications I see today have
little or no grounding in traditional ontologies, upper or otherwise.
I do believe that the descriptive capability that the SW languages
introduce offers the potential for more useful web applications.    (04)

> For more arguments, read my answer to Hans, artfully detecting one problem
> after another. Take another question which he raised, now regarding
> representation of weight and its values. And what kind of funny advice he is
> getting:
> ''Note well that the meaning of the "properties" minWeight and maxWeight are
> very different from the property weight.  The former two are, perhaps,
> properties of the class whereas the latter one is a property of instances of
> the class.'' </PPS>.    (05)

This seems reasonable. If I wish to take my heavy vehicle over a
bridge, I would need firstly to discover the maximum weight the bridge
could support - or to put it another way, that property shared by all
objects in the set of things that could get over the bridge. Next I
would need to consider the weight of my individual vehicle.    (06)

> As i wrote before:
> ''But mostly important to tell the formal properties (attributes) from the
> ontological properties, which are
> generally classified as:
> 1. the property of being a substance (object), substantial properties;
> 2. the property of being a state (quantity or quality), quantitative and
> qualitative properties;
> 3. the property of being a process (change, action, operation), dynamic,
> functional, operational properties;
> 4. the property of being a relationship; relational properties per
> se.''</ASHA>
> In the special case mentioned above, Hans ran into one of the basic kind of
> property, Quantity, having two major divisions: continuous magnitude and
> discontinuous multitude (discrete quantities), commensurable to the degree
> of being measurable by numbers. Next, a real ontology language may indicate
> that there are at least two modes of magnitudes: of geometry and of physics.
> The physical quantities (or dimensions) cover space (length, breadth,
> width), time, mass, weight, the dimensions of motion as velocity,
> acceleration and momentum, as well as temperature, heat, entropy, and each
> dimension is specified by its unit of measurement and measured by the
> physical instruments, such as clocks, rulers, balances, etc., through
> selected mathematical procedures. So, the gravitational force of weight here
> is a dimension which measures the heaviness of objects (as 'body weight'),
> having a lawful relationship to the mass of objects, with a specific range
> of values for different physical objects [for the quantity fundamentals,
> look up Wikipedia, Quantity].    (07)

Going back to the bridge, it isn't necessary for a piece of software
to know about gravity to determine that a 100 ton truck can't get over
a bridge with an upper weight limit of 10 tons. A complete and
accurate ontological model of reality is not necessary to determine
100 > 10.    (08)

> Lesson, neither formal language can represent and reason about reality,
> telling you the nature and fundamental kind of things, but the real world
> ontology language, which must be on the top of any 'semantic web'
> archirecture, unless you want to kill your applications.    (09)

For the reasons given at the start, I'm not really qualified to talk
in terms of the nature and fundamental kinds of things. But I am
qualified (by experience) to say it is possible to usefully represent
and reason about reality with the kinds of languages found in the
SemWeb stack.    (010)

For example, software can be used to determine whether two people are
likely to have an opportunity to meet each other at a conference using
very simply constructed representations of the information, like the
class of Person and Location and properties like date/time. (see [1]).
There's no need to anchor this information in the fundamental nature
of reality, in fact being able to work with loose approximations has a
lot of advantages - notably that no agreement  is necessary on the
nature of reality beyond what is required within the scope of the
problem.    (011)

My personal upper ontology features the class Wife (containing one
individual), Dog (ditto), Cat (lots). The first two have the
significant property slot likesWalking, all three have isHungry. This
ontology usefully captures the nature of about 80% of my own reality.
However, through Semantic Web languages, information expressed using
these terms is potentially compatible with that expressed in any other
formalisation of the world.    (012)

Danny.    (013)

[1] http://esw.w3.org/topic/SparqlCalendarDemo    (014)

--    (015)

http://dannyayers.com    (016)

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