Danny,
Please see my comments interspersed. (01)
respects,
Azamat (02)
> ----- Original Message -----
> From: "Danny Ayers" <danny.ayers@xxxxxxxxx>
> To: "ONTAC-WG General Discussion" <ontac-forum@xxxxxxxxxxxxxx>
> Sent: Monday, April 03, 2006 7:03 PM
> Subject: Re: [ontac-forum] Re: Semantic Layers (Was Interpretation
> ofRDFreification)
>
>
> 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,
>
> Ok, but I know on which lists to lurk ;-)
>
>> 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.
>
> 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. (03)
This capacity comes from a core set predicable relations of: ''definition'',
''class'', ''individual'', ''property'', ''sameness'', ''difference'', and
''inheritance''. It is nothing to do with this sort of formal language. (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>.
>
> 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. (05)
It is not so complicated. In UFO, there are basic ontological assumptions
for making a situational reasoning, such as
There are substances (objects) in the world;
The world can be in different states;
Objects have states;
Object are subject to changes;
Changes cause other changes as effects;
A state is the union of all the values of the properties which an object
(system) has at a certain time, etc. (06)
Basing on such axioms, your reasoner may conclude that your car is a
physical system ( a vehicle) marked by specific physical qualities and
quantities, as mass and weight, position, velocity, and all the properties
take some range of values, with upper limit and lower limit. The same
reasoning applies for the bridge. (07)
>
>> 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].
>
> 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.
>
>> 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.
>
> 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. (08)
See above. Here is a main problem: it's a push-down stack without any
ontological groundwork. (09)
> 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, (010)
Actually, there is; for your real-life applications should 'understand' what
does it mean to be a person, to have a location, etc. (011)
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.
> (012)
> 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. (013)
> However, through Semantic Web languages, information expressed using
> these terms is potentially compatible with that expressed in any other
> formalisation of the world. (014)
You may have your individual ontological commitments specific a certain
domain (your home, a domain-specific ontology). Important, these commitments
are not casual but must comes form one underlying reality, unifying
ontological context. For then the application can tell your most meaningful
information about you pets and wife, their properties, possible behavior,
and relationships. That they are living beings, have life, can eat, have
different moods, can love you, etc. (015)
> Cheers,
> Danny.
>
> [1] http://esw.w3.org/topic/SparqlCalendarDemo
>
> --
>
> http://dannyayers.com
>
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