From:
ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of sean barker
Sent: Wednesday, March 10, 2010 2:34 PM
To: ontolog-forum@xxxxxxxxxxxxxxxx
Subject: Re: [ontolog-forum] Re Foundation ontology, CYC, and Mapping
Duane
Chris Menzel was right in saying it's not that subtle. The term
type here refers to the abstract data type used to reify the concept - for
example, does one reify a latitude as a real number, a fixed precision decimal
number, or as a triple of integers for degree, minute, second.
This is distinct from the problem 3D v 4Dism that Matthew referred
to.
One of the problems I have not seen discussed much - possibly because
I have been looking in the wrong place - is the relation in ontology
languages between concepts and their reification, as opposed to the
relation between different concepts. For example, I would regard 2D and 3D
points as referring to different concepts, whereas Cartesian co-ordinate
systems v. polar co-ordinate systems for a 2D point
as different reifications of the same concept. Looking at languages
like OWL, it seems that the reification is identified with form
of the concept, as if there is only one way of reifying it.
Having two different reifications of a concept should not be a
major semantic challenge, the challenge is that, unless you account for the
different reifications, the systems cannot interoperate. However there may be
practical problems concerning the adequacy of the reifications. See, for
example, Cliff B Jones, "Systematic Software Development using VDM",
Chapter 8 on Data reification for a more detailed treatment.
The converse is what John Sowa keeps insisting on, that
interoperation happens mostly at the level of middle ontologies. In this case,
there is some morphism between the reifications - or at least a subset of the
reifications - which can be used for interoperation. For example, there is a
simple morphism between points in Euclidean space and those in a homogenious
co-ordinate system. In one dimension this is
E(x) -> H(x, 1) and H(x, 1) -> E(x).
This breaks down for points of the form H(x, 0), but then
Eucllidean spaces doesn't have a lot to say about points at infinity.
Sean Barker
Bristol
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Duane
Nickull
Sent: 09 March 2010 22:41
To: [ontolog-forum]
Subject: Re: [ontolog-forum] Re Foundation ontology, CYC, and Mapping
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Sean:
For the second of these (conflicts when the same concept is represented by
different types), can you elaborate a couple of examples (no hurry). I
just want to make sure I have a good idea of this.
Duane
On 3/9/10 2:30 PM, "sean barker" <sean.barker@xxxxxxxxxxxxx> wrote:
Apologies
for slow response to a couple of requests for sources on semantic
incompatibilities.
This is the table we generated internally, based partly on older database work
Semantic
Incompatibilities
Naming
Conflicts
When
objects representing the same concept may contain dissimilar names:
conflicts due to either homonyms or synonyms.
Type
Conflicts
When
the same concept is represented by different types.
Key
Conflicts
When
different keys are assigned to the same concept in different schema.
Behavioural
Conflicts
When
different insertion/deletion policies are associated with the same class
of objects in different schemata. e.g. deleting an object may leave an
“empty” object rather than a “null reference”.
Missing
Data
When
different attributes are defined for the same concept.
Levels
of Abstraction
When
information about an entity is stored at dissimilar levels of detail.
e.g. ‘name’ versus ‘first_name’ and
‘last_name’.
Identification
of Related Concepts For example, two entities belonging to two
different databases may not be equivalent but one entity may be a
generalisation of the other entity.
Scaling
Conflicts
When
the same attribute of an entity is stored in dissimilar units.
it
is based on/taken from
[1]
Aykut
Firat, Information Integration Using Contextual Knowledge and Ontology
Merging. MIT (Sloan School of Management) Ph. D thesis, September 2003.
[1]
M.
P. Reddy, B. E. Prasad, P. G. Reddy, Amar Gupta, A Methodology for
Integration of Heterogeneous Databases, IEEE Transactions on Knowledge and
Data Engineering, Vol. 6, No. 6, December 1994.
There are some other papers dating from the mid-nineties, but they have not
survived my various office moves.
Sean
Barker
Bristol