General Formal Ontology (GFO)
type: Ontology
created: 2006-08-28
modified: 2024-11-18
license: http://creativecommons.org/licenses/by/4.0/
doi: 10.5281/zenodo.5205419
preferred namespace prefix: gfo
preferred namespace URI: https://w3id.org/gfo/
repository: GFO
imports: base
prior version: https://w3id.org/gfo/release/2024-07-05
version IRI: https://w3id.org/gfo/release/2024-11-18
version info: 2024-11-18

Abstract
type: Class
comment: Abstract individuals are independent from time and space (they are not in time and space). Examples: the number "2" or pi.
subclass of: Individual
disjoint with: Concrete
disjoint with: Space time

Action
type: Class
comment: Actions are occurents which are caused by some presential (the agent) at every (inner and outer) time-boundary of the chronoid framing the occurent.
subclass of: Occurrent
subclass of: Restriction
  on property: has agent
  some values from: Presential

Category
type: Class
comment: Categories satisfy the following conditions: (1) Categories can be instantiated; (2) Categories can be predicated of other entities. Categories are defined intensional-with-an-s. They are, therefore, closely related to language.
subclass of: Item
disjoint with: Individual

Change
type: Class
comment: A change in the technical sense refers to a pair of process boundaries. Either at coinciding boundaries (then it comes close to notions like ``punctual'' or ``instantaneous event'' as well as ``moment'' -- in a temporal reading), or at boundaries at the opposite ends of a process of arbitrary extension. The notion of change is relative to contradictory conditions between which a transition takes place. These contradictions refer to some collection of pairwise disjoint universals.
subclass of: Occurrent
disjoint with: History
disjoint with: Process

Chronoid
type: Class
comment: Chronoids are entities sui generis. Every chronoid has exactly two extremal and infinitely many inner time boundaries which are equivalently called time-points.
subclass of: Temporal region

Concrete
type: Class
comment: Concrete individuals have a relation to time or space (they are in time and space).
subclass of: Individual
disjoint with: Space time

Configuration
type: Class
comment: We consider a collection of presential facts which exist at the same time-boundary. Such collections may be considered themselves as presentials, and we call them configurations. It is further required that configurations contain at least one material object.
subclass of: Presential
disjoint with: Material boundary
disjoint with: Material object

Configuroid
type: Class
comment: Configuroids are, in the simplest case, integrated wholes made up of material structure processes and property processes.
subclass of: Process

Continuous change
type: Class
comment: For the purpose of formalizing continuous changes, a minimal chronoid universal D(c) is employed in order to capture the idea of observable differences during certain chronoids, whereas the change itself does not allow the observation of a difference. The predicate change(e1,e2, u1, u2, u, D(c)) is intended to formalize this approach. Continous changes occur over time (a chronoid).
subclass of: Change
equivalent class: Intrinsic change

Continuous process
type: Class
comment: Processes where all non-coinciding internal boundaries are intrinsic changes. These turn out as purely continuous processes, described e.g. in physics by differential equations.
subclass of: Continuous
subclass of: Process
disjoint with: Discrete process

Discrete process
type: Class
comment: Discrete processes are made up of alterations of extrinsic changes and states.
subclass of: Discrete
subclass of: Process

Entity
type: Class
comment: Everything which exists is called an entity.
equivalent class: Class
  union of: Item
  union of: Set

Extrinsic change
type: Class
comment: Deprecated. Extrinsic changes are represented by change(e1,e2, u1, u2, u), where e1 and e2 are a pair of coincident process boundaries, and u1 and u2 are disjoint sub-universals of u.
subclass of: Change
disjoint with: Intrinsic change
equivalent class: Instantanuous change

Function
type: Class
comment: A function F is a universal (conceptual structure) defined in purely teleological terms with respect to a given goal G which commonly is ascribed by means of has-function relation to entities that are the realizations of the function F, execute such a realization or are intended to do it.
subclass of: Concept

History
type: Class
comment: Histories consist of a number of process boundaries. We assume that any history can be embedded into a process, which then forms a foundation of the history. If it were not for this foundation, one would face the problem of singling out the right boundaries in order to get a natural history: It is not sensible to measure the temperature of a patient first, then determine his weight, followed by measuring his blood pressure and to consider these strangely arbitrary process boundaries as a history of the patient's body data.
subclass of: Occurrent
disjoint with: Process

Individual
type: Class
comment: Individuals are entities which cannot be further instantiated.
subclass of: Item
subclass of: Class
  complement of: Restriction
    on property: instantiated by
    some values from: Item
equivalent class: Class
  intersection of: Class
    union of: Abstract
    union of: Concrete
    union of: Space time
  intersection of: Class
    union of: Dependent
    union of: Independent
  intersection of: Class
    union of: Role
    union of: Class
      intersection of: Individual
      intersection of: Class
        complement of: Role

Instantanuous change
type: Class
comment: Instantanuous changes are represented by change(e1,e2, u1, u2, u), where e1 and e2 are a pair of coincident process boundaries, and u1 and u2 are disjoint sub-universals of u. Instantanuous changes are therefore changes of properties on two coinciding time boundaries.
subclass of: Change

Intrinsic change
type: Class
comment: Deprecated. For the purpose of formalizing intrinsic changes, a minimal chronoid universal D(c) is employed in order to capture the idea of observable differences during certain chronoids, whereas the change itself does not allow the observation of a difference. The predicate change(e1,e2, u1, u2, u, D(c)) is intended to formalize this approach.
subclass of: Change

Item
type: Class
comment: An item is everything which is not a set. Also called ur-element.
subclass of: Entity
subclass of: Class
  complement of: Restriction
    on property: has member
    some values from: Entity
disjoint with: Set
equivalent class: Class
  union of: Category
  union of: Individual

Level
type: Class
comment: An ontological level, which is sth. more restricted and "part of" some gfo:Stratum.
subclass of: Ontological layer
subclass of: Restriction
  on property: abstract part of
  some values from: Stratum
disjoint with: Stratum

Material object
type: Class
comment: A material structure is an individual which satisfies the following conditions: it is a presential, it occupies space, it is a bearer of qualities, but other entities cannot have it as quality, and it consists of an amount of substrate, and it instantiates a persistant ("has identity").
subclass of: Discrete presential
subclass of: Restriction
  on property: framed by
  some values from: Topoid
subclass of: Restriction
  cardinality: 1
  on property: framed by
equivalent class: Material structure

Material persistant
type: Class
comment: Material persistants are particular universals whose instances are material structures; they are related to those entities which are called sometimes continuants or objects, as apples, cars or houses. Material persistants capture the phenomenon of persistance through time of a material object. A material persistant P satisfies a number of neccessary conditions. For every material persistant P there exists a process P such that the set of instances of P coincides with the set of process-boundaries of P. This implies the existence of a chronoid c such that for every time-point t of c there exists exactly one instance of P at time point t.
subclass of: Persistant
subclass of: Restriction
  all values from: Material object
  on property: instantiated by

Material stratum
type: Class
comment: According to (Poli,2001), the basic structure of the material stratum is a distinction of physical, chemical and biological levels. These levels can be further refined.
subclass of: Stratum

Mental stratum
type: Class
comment: In accordance with the work of R. Poli, we divide the psychological/mental stratum into the layer of awareness and the layer of personality. Awareness comprises most of what is studied by cognitive science (perception, memory, reasoning, etc). Personality on the other hand concerns the phenomenon of will and the way in which someone reacts to her experiences.
subclass of: Stratum

Occurrent
type: Class
comment: Occurents have temporal parts and thus cannot be present at a time-boundary. Time belongs to them, because they happen in time and the time of the occurent is built into it. The relation between an occurent and a chronoid is determined by the projection relation. Occurents are also called generalized processes in the GFO.
subclass of: Concrete
disjoint with: Presential

Ontological layer
type: Class
comment: Ontological_layer, all of its subconcepts and the properties layer_of and on_layer are work in progress in a premature beta state.
comment: a collective term for gfo:stratum and gfo:level
subclass of: Category
version info: Beta

Persistant
type: Class
comment: Persistants are GFO's way to capture identity over time. GFO pursues an approach which accounts for persistence by means of a suitable universal whose instances are presentials. Such universals are called persistants. These do not change and they can be used to explain how presentials which have different properties at different times can nevertheless be the same.
subclass of: Universal
subclass of: Restriction
  on property: instantiated by
  some values from: Presential

Presential
type: Class
comment: A presential exists wholly at exactly one time boundary.
subclass of: Concrete
subclass of: Individual
subclass of: Restriction
  on property: exists at
  some values from: Time boundary
subclass of: Restriction
  cardinality: 1
  on property: exists at

Process
type: Class
comment: Processes are a special kind of occurent. Processes are directly in time, they have characteristics which cannot be captured by a collection of time boundaries.
subclass of: Occurrent

Processual role
type: Class
comment: Processual roles are dependent processes. They are roles with a process as context.
subclass of: Process
subclass of: Role
subclass of: Restriction
  on property: role of
  some values from: Process
disjoint with: Relational role
disjoint with: Social role

Property value
type: Class
comment: The concept of a property value reflects a relationship between the property of x and the same property as exhibited by another entity y.
subclass of: Concrete
subclass of: Dependent
equivalent class: Restriction
  on property: value of
  some values from: Property

Set
type: Class
comment: Set is a category pertaining to the individuals in the ZFC set theory.
subclass of: Entity

Situation
type: Class
comment: A situation is a special configuration which can be comprehended as a whole and satisfies certain conditions of unity, which are imposed by relations and categories associated with the situation. Herein, we consider situations to be the most complex kind of presentials.
subclass of: Configuration

Situoid
type: Class
comment: Situoids are processes whose boundaries are situations and which satisfy certain principles of coherence, comprehensibility, and continuity. They are regarded as the most complex integrated wholes of the world. A situoid is, intuitively, a part of the world which is a coherent and comprehensible whole and does not need other entities in order to exist. Every situoid has a temporal extent and is framed by a topoid.
subclass of: Configuroid

Social stratum
type: Class
comment: On the one hand, the social stratum is divided into Agents and Institutions. Agents are the bearers of the social roles that humans play. Institutions are defined as systems of interrelated social components. On the other hand, a social system can be seen as a network in which businesses, politics, art, language (and many other facets) both present their own features and influence each other.
subclass of: Stratum

Space
type: Class
comment: GFO uses Brentano space.
subclass of: Space time
disjoint with: Time

Spatial boundary
type: Class
comment: Boundaries of regions are surfaces, boundaries of surfaces are lines, and boundaries of lines are points. As in the case of time-boundaries, spatial boundaries have no independent existence, i.e. they depend on the spatial entity of which they are boundaries.
subclass of: Space
disjoint with: Spatial region
equivalent class: Restriction
  on property: spatial boundary of
  some values from: Space

Spatial region
type: Class
comment: Space regions are mereological sums of topoids.
subclass of: Space

State
type: Class
comment: A process without an instantanuous change at any of its inner time boundaries is called a state.
subclass of: Process

Stratum
type: Class
comment: According to (Poli, 2001, 2002) (based on the philosopher Hartmann) we distinguish at least three ontological strata of the world: the material stratum, the mental/psychological stratum, and the social stratum stratum. Every entity of the world participates in certain strata and levels. We take the position that the layers are characterized by integrated systems of categories. Hence, a layer can be understood as a meta-category whose instances are categories of certain kinds. Among these levels specific forms of categorial and existential dependencies hold. For example, a mental entity requires an animate material object as its existential bearer.
subclass of: Ontological layer

Temporal region
type: Class
comment: Time Regions are defined as the mereological sum of chronoids, i.e. time regions may consist of non-connected intervals of time.
subclass of: Time
disjoint with: Time boundary

Time
type: Class
comment: The time model of GFO is based on Brentano and the glass continuum of Allen&Hayes.
subclass of: Space time

Time boundary
type: Class
comment: Time boundaries depend on a chronoids (i.e. they have no independent existence) and can coincide.
subclass of: Time
subclass of: Restriction
  on property: time boundary of
  some values from: Chronoid

Topoid
type: Class
comment: Topoids are connected compact regions of space. They have spatial boundaries.
subclass of: Spatial region

Universal
type: Class
comment: Universals are immanent universals. They exist in re.
subclass of: Category
subclass of: Restriction
  on property: instantiated by
  some values from: Item

Value space
type: Class
comment: Property values usually appear in groups which are called value structures, value spaces or measurement systems. Each of these structures corresponds to some property. More intuitively, one could say that the property may be measured with respect to some measurement system. For instance, sizes may be measured with the values ``small'' ``big'' or ``very big'', which are the elements of one value structure. The notion of a value structure of a property is similar to a quality dimension in (Gardenfors, 2000). Further, value structures are related to quality spaces in DOLCE (Masolo, 2003}. A quality space consists of all ``quales'' (our property values) of some ``quality'' (our property). Often it seems to be the case that a notion of distance can be defined, and that certain layers of value structures are isomorphic to some subset of real numbers, which allows for a mapping of values to pairs of a real number and a unit, as in the case of ``10 kg''.
subclass of: Universal

abstract part of
type: ObjectProperty
type: TransitiveProperty
comment: The abstract part-of relation is denoted by p(x,y); the argument-types of this relation are not specified, i.e. we allow arbitrary entities to be arguments. We assume that p(x,y) satisfies the condition of a partial ordering, .i.e. the following axioms: reflexivity, antisymmetry and transitivity.
domain: Item
range: Item
inverse of: abstract has part

depends on
type: ObjectProperty
comment: This relation captures the notion of existential dependence.
domain: Item
range: Item

goal of
type: ObjectProperty
comment: "goal" here refers to "final state" in (Burek, 2006).
domain: Class
sub property of: function determinant of
inverse of: has goal

instance of
type: ObjectProperty
comment: The instantiation relation holds between a category and an item. It is not a relation between categories and individuals due to higher order categories such as "species".
domain: Entity
range: Category

left boundary of
type: ObjectProperty
type: InverseFunctionalProperty
comment: Left boundary of a chronoid.
inverse of: has left time boundary

requirement of
type: ObjectProperty
comment: "requirement" here refers to "initial state" in (Burek, 2006).
domain: Class
sub property of: function determinant of
inverse of: has requirement

right boundary of
type: ObjectProperty
type: InverseFunctionalProperty
comment: Right boundary of a chronoid.