Hans inquired:
''Is it possible that owl:Individual, that once existed [1], was meant to be
the class of REAL individuals in a REAL world?''
Hans decided:
''I have thrown out the owl:Thing. Much easier to read for humans.'' (01)
The class/thing distinction makes here all the difference, and hardly you
will get any explicit account from the owl languages authors. For its a
central issue in all current activities of building top ontologies (SUO,
USECS, ONTAC, etc.) and SW languages (RDFS, OWL, OWL1.1, etc), and it
touches the sorest spot in the whole logical enterprise of OWL ontology
passing as an ontological undertaking 'breaking all implicit and explicit
assumptions of computing science'. (02)
The status, validity, and expressivity of any general representational
languages and technologies are chiefly determined by the ways of treating
the things in the world. And there are usually three main choices widely
practiced: one can define 'Thing' as an individual, a class of individuals,
or the universal class, i.e., the class of all classes. Or, in terms of
quantities, as a fixed value (constant), an individual variable, and a class
variable.
The narrow view of thing as [an entity with a specific identity] has its
long history as ('a primary substance', 'a bare individual', etc.) and was
supported by such modern logicians and ontologists as Quine, for whom 'to be
is to be a value of a bounded variable'.
In the OWL domain, the extension of the construct owl:Thing has only
individual things, being void of other essential meaningful dimensions. In
the biological classificatory system, this corresponds to the level of
species whose members share a set of essential features and bound by a
membership relationship between an individual and its class. Note you can
subject a collection of individuals, say, the totality of human beings, to
further divisions and subdivisions, such as man and woman, White or Black or
Yellow or Red, the aged or the young, the poor or the rich, the working
class or the professional class; underworld, lower class, middle class or
higher class, etc. Yet they are not (genetically) essential classifications,
and you are still in the domain of individuals, for even infinitely
increasing the number of individuals doesn't allow you to create a new
class or species or kind. Therefore we say about two types of difference, in
kind or in degree.
But a fundamental position is to consider Thing (or Entity) as the class of
classes (the set of subsets) at least; at best as the class of all classes
(the universal set of all sets), hierarchically ordered by inclusion
(containment) relationships (or whole-part relationships). Since, as the
class variable, Thing will have as its values lower classes and subclasses
as well, or the type of variables whose values are also variables (as a
metasyntactic variable 'foobar', where "the value of f(foo, bar) is the sum
of foo and bar"). (03)
Returning to our sheep, the OWL semantic language. To be blunt, without
diplomatic evasion and sublety, as a general ontological language it is
fundamentally defective and it would be a technological catastrophe to use
this as 'Ontology Infrastructure for the Semantic Web' [1] for several
evident reasons. (04)
First, the polar terms of the OWL vocabulary are individuals, classes, and
properties, which are, above all, mathematical and logical abstract terms
without real content and substance, i.e., without reference to reality. To
be an ontology, its basic construct should be the class of Thing equal to
the class of all entity classes, of which the most fundamental are the class
of Substance (Object), the class of State (Quantity and Quality), the class
of Process (Change or Action) and the class of Relationship. Each one of
these Entity classes is organized as a hierarchy of subordinate classes
(kinds and types), where particular levels occupied by such individual
things (or instances, particulars, and concrete entities) as objects,
specific states, unique events and specific connections. Crucially,
'definition', 'class', 'property' and 'statement' (see Topics) should be
filled up with real contents and meanings. Even you may have an
idiosyncratic set of ontological commitments as pivotal environmental and
cognitive universals, still they must be ontological classes, rather than
logical entities. (05)
Second, the construct of owl:Property, with its two basic types: owl:
ObjectProperty (mapping individuals to individuals) and owl:DatatypeProperty
(mapping individuals to datatype values). In fact, there are monadic and
diadic properties; essential and accidental; atomic, transient, complex, or
emergent; particular and general, etc. 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. (06)
Thus, in the owl domain, owl:Property is badly narrowed to the property of
being a formal (functional) relationship, direct and inverse; without
explicitly identifying the nature of relations between the connected
components, spatial, temporal, causal, whole/part, syntactic, semantic,
pragmatic, etc. Moreover dealing with only two main types of property: owl:
ObjectProperty and owl:DataProperty, existing as disjoint constructions,
discard any hope of comensurability between magnitudes (entity variables)
and multitudes (numbers), forget measurement, assigning number to things.
There are other defects and contradictories, particularly in its
(subsumption) logic, which may take more time and patience, so i better stop
for now. (07)
Moral. In difference to the OWL people's feelings and hopes, it is not an
ontology but a sort of formal language involving a functional, formal logic,
and just need be properly renamed as FoLWL or LWL, Logical Web Language.
Accordingly, the semantic web into the formal semantic web, which is a poor
abstraction of the real (semiotic) Web [as it' has recently turned out],
asking for a firm conceptual foundation, n-relational ontology of things and
its complement, ontological semiotics. Or, put away for a long time your
lofty hopes about real-life knowledge applications and web-based intelligent
systems capable to represent and reason about the world, and have instead a
'wonderweb' blown off billions and billions of public funds. It seems
something must be done to stop this fast-going and widely spreading pandemic
of nescience. (08)
Hans, about you specific problem, you are on the right track. On the
ontological abstract level, a pump is a specific class (species) of Thing [>
substance > physical substance > artefact > device > mechanism > mechanical
device] marked by a specific [functional property] of moving fluid and gas
[substance] by suction or pressure [process]. This is all about its
intensional meaning, its primary definition, while its extension is made up
of all types of pumps differered by the type of working substance used and
ways of operations, constructions, etc.: gas pump, oli pump, water pump,
lift pump, hydraulic pump, hand pump, foot pump, you may continue such a
division at infinitum. In the actual world of particular things, a pump is
an individual existing as a concrete physical object, a unique instance of a
class of physical devices.
All the confusion comes from the replacement of fundamental ontological
category of Thing or Entity with a empty logical category owl:Class. And
please don't throw 'things' away, as the child from the bath, rather discard
empty 'classes', the bath itself. (09)
with all respects, (010)
Azamat Abdoullaev (011)
----- Original Message -----
From: "Hans Teijgeler" <hans.teijgeler@xxxxxxxxxxx>
To: "'Dave Reynolds'" <der@xxxxxxxxxxxxxxx>
Cc: "'SW-forum'" <semantic-web@xxxxxx>
Sent: Friday, March 31, 2006 10:27 AM
Subject: RE: owl:Class and owl:Thing (012)
> The class Pump is such a case where it is both an owl:Class and an
> individual, as a member of the class ClassOfInanimatePhysicalObject. Yet
> it has not been declared as owl:Thing. I understand from you that that is
> OK.
>
> Is it possible that owl:Individual, that once existed [1], was meant to be
> the class of REAL individuals in a REAL world?
>
> Regards,
> Hans
>
> [1] http://wonderweb.semanticweb.org/deliverables/documents/D1.pdf
>
> =========================================================================
>
> -----Original Message-----
> From: Dave Reynolds [mailto:der@xxxxxxxxxxxxxxx]
> Sent: Thursday, March 30, 2006 23:58
> To: Hans Teijgeler
> Cc: SW-forum
> Subject: Re: owl:Class and owl:Thing
>
> Hans Teijgeler wrote:
>
>> In OWL-Full it is possible to have a class that also is an individual
>> in the context of a class-of-class. We have that a lot. Now my
>> question is whether or not I shall call the same object an owl:Class
>> when it is in the role of class, and call it an owl:Thing when it is
>> in the role of individual. If not, what shall prevail? Or must I declare
> it twice?
>
> You don't *need* to declare it at all in OWL/full.
>
> If you use a resource in the role of a class then it can be inferred to be
> a
> class. For example, if you use it as the object of an rdf:type statement
> or
> in an rdfs:subClassOf statement then it can be inferred to be an
> rdfs:Class.
> In OWL/full rdfs:Class and owl:Class have the same extension.
>
> Similarly it can be inferred to be an owl:Thing (for trivial reasons in
> OWL/full) and probably some subclass of owl:Thing based on the
> domain/range
> of whatever properties you apply to it.
>
> However, it may be useful for human readers of your ontology if you
> document
> it's dual nature by declaring both it's types explicitly along with
> appropriate rdfs:comments.
>
> Dave
>
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> (013)
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