


Overview
General Formal Ontology (GFO)

The basic level of GFO contains all relevant toplevel distinctions and
categories.
One should distinguish between primitive categories (whose instances are
individuals), and higher order categories. In the present document we
consider primitive categories and the category of
persistants (which is a special category of second order). These categories
will be be extended in the future using a number of nonprimitive categories.
Primitive categories and persistants of the basic level will be
discussed further
in the following sections and are the main content
of the current report. All basic relations and categories are presented as
settheoretical relations and settheoretical predicates. The ontology of
the basic level is expressed in a formal language with restricted expressive
power. We use a common (firstorder) language througout all levels,
but constrain the expressive power at every level, mainly by restricting the
scope of the quantifiers. At the basic level, an unrestricted quantification
over categories is not allowed. The basic predicates as
, , , , and others, are considered
(understood) to be metacategories
over the object level (domain) ontologies. is a predicate whose
elements contain those categories, which are persistants. The notion
of a persistant is the result of an ontological analysis of notions as
continuant,
or endurant. One may extent the vocabulary of the basic level by adding further
predicates, whose elements are categories. Examples of such predicates
are stratumpredicates, is a predicate that contains
all categories of the material stratum,
is a predicate
that contains all categories of a certain structural type tp.
Categories which are not contained within the basic level we call domain
categories. Domain categories are related to a certain part of the real
world, and on the domain level they are not presented (and considered) as
sets, but as entities of its own. Formally, the vocabulary at the basic level
of GFO is extended by additional constants denoting proper categories or
individuals. If, for example, denotes a domain category we write
instead of , indicating that is an instance of
. For the purpose
of abbreviation we write sometimes instead of .
Domain categories
may be linked in a simple way to the basic level predicates of GFO, using
domainupper linking axioms. For example,
if we want to say that a certain domain category is a process category
(i.e., all its instances are processes) we write the following linking
axiom:
, or, by using the abbreviation
. DomainUpperLinking axioms exhibit
an ontological embedding of a domain ontology into a foundational ontology.
We introduce particular notations for treating the persistants.
If is a persistant then denotes the instance of at the
timepoint ,
and the relation is defined by
.
Robert Hoehndorf
20061018

