Mike, Doug, and Deborah, (01)
MB> We are developing a formal semantic model of terms in the
> financial services industry, and to do this we are using
> the underlying concepts of OWL but restating these in English. (02)
That sounds like a good strategy. Do you have tools to do the
mapping in both direction? (03)
MB> We refer to the OWL Classes as "Things" and properties as
> "Facts" namely "Relationship Facts" and "Simple Facts"
> respectively. These are modeled in a UML modeling tool from
> which we produce both diagrams and spreadsheets, for review
> via a website (this is at www.hypercube.co.uk/edmcouncil ). (04)
The general principle sounds good, but "things" tend to be nouns.
What about concepts represented by verbs and adjectives? (05)
By the way, the draft OMG standard for "a Foundational Subset
for Executable UML Models (FUML)" is defined in Common Logic: (06)
http://www.omg.org/spec/FUML/1.0/Beta2/ (07)
DF> There seems to be two definitions of a taxonomy used in this
> list.
> 1. A tree structure of subtypes
> 2. A DAG (directed acyclic graph) of subtypes.
>
> I'm more comfortable with using the term "taxonomy" to refer
> to #1 and "hierarchy" to refer to #2. (08)
It's necessary to distinguish structure from content. The words
'tree', 'DAG', and 'hierarchy' refer to structure, independent
of what the nodes of the structure represent. (09)
The terms 'taxonomy' and 'ontology' refer to the content, which
could be represented by various kinds of structures. For example,
a taxonomy of living things is usually a tree because the normal
way genes are inherited creates a tree. But a taxonomy of tools
could be a DAG if you have some kinds of multipurpose tools. (010)
DM> Faceted classification is a big plus of Omniclass. It allows
> something like a brick to be the brick itself, part of a wall
> assembly, part of a hospital, from a manufacturer in Ohio.
> Hospitals can also be made of other kinds of wall assemblies
> so there are no straight lines or consistent elements for
> every project or building type. (011)
Any ontology that is adequate for describing physical objects
must distinguish an open-ended number of relations: (012)
1. Type/Subtype for the basic hierarchy. (013)
2. Type/Instance for the physical objects of any given type. (014)
3. Whole/Part for types that are constructed from other types. (015)
4. Object/Material for types that are made of certain kinds
of material. (016)
5. location, point-in-time, duration, mathematics, etc. (017)
Facets are monadic predicates or relations, and a faceted
system allows arbitrary conjunctions of facets. That is
a very simple and useful representation for many purposes.
But eventually you need more general relations. (018)
For example, you can bundle lots of other structure into
a single monadic relation, such as isMadeOfWood, isFromOhio,
isThreeStoriesHigh, wasBuiltTenYearsAgo, isUsedAsHospital,
or isOnTheOppositeSideOfTheStreetFromHospital. But
eventually, this gets to be borderline ridiculous. (019)
That is why you need to embed any special-purpose notation
within a larger, more expressive framework. (020)
When description logics were invented in the 1970s, they
were used in the T-box (terminology component) to define
a type hierarchy. But the complete system also contained
an A-box (assertion component) that used a more expressive
logic, such as a rule-based (Horn clause) language, full
first-order logic, or more. (021)
John (022)
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