gUFO: A Lightweight Implementation of the Unified Foundational Ontology (UFO)

A gufo:Individual that does not exist in space-time in the same way as a gufo:ConcreteIndividual does. A gufo:AbstractIndividual has no spatiotemporal qualities in its own right. Hence, it does not make sense to ask how much space it now occupies (Gideon, 2018) and when it was created or destroyed.

Examples include the number ten, the null set, and the proposition that 'Obama was the president of the United States'.

Rosen, Gideon, "Abstract Objects", The Stanford Encyclopedia of Philosophy (Winter 2018 Edition), Edward N. Zalta (ed.), https://plato.stanford.edu/archives/win2018/entries/abstract-objects/

A gufo:Type whose instances are abstract individuals.

Instances of gufo:AbstractIndividualType are subclasses of gufo:AbstractIndividual.

Examples include the types "NaturalNumber", "Set", "Proposition".

A gufo:NonRigidType that applies contingently to all its instances (see Guizzardi, 2005, chapter 4).

Examples include the gufo:Phase "Child", the gufo:PhaseMixin "InfantAnimal", the gufo:Role "Student", and the gufo:RoleMixin "Customer".

A gufo:Endurant that depends on at least one other concrete individual for its existence. A gufo:Aspect is a characteristic or trait of a concrete individual that is itself conceived as an individual.

Examples include: intrinsic physical aspects, such as the Moon's mass, Lassie's fur color; mental dispositions, such as Bob's math skills, his belief that the number one is odd; as well as relational aspects, such as John's love for Mary and the marriage between John and Mary.

The specific sort of existential dependence connecting aspects to their bearers is called inherence.

Corresponds to "Moment" in Guizzardi (2005).

Also termed "property instance", "particularized property", "individual accident", or "(variable) trope" in the philosophical literature.

A gufo:EndurantType that is both non-sortal and rigid. It captures essential properties that apply to instances of different kinds.

For example, "PhysicalObject" may be considered a gufo:Category, encompassing objects such as cars, planets, trees. "Agent" may be a gufo:Category that classifies both people and organizations.

A complex gufo:Object whose parts (the members of the collection) have a uniform structure (i.e., members are conceived as playing the same role in the collection). Collections may have a fixed or variable membership, which can be asserted using gufo:FixedCollection and gufo:VariableCollection respectively.

Examples include a deck of cards, a pile of bricks, a forest (conceived as a collection of trees), and a group of people.

Collections in many cases constitute a functional complex. For example, a pile of bricks may constitute a wall, a group of people may constitute a football team.

A gufo:Collection may be decomposed into "smaller" collections. For instance, a group of people may be decomposed into a group of English speakers and a group of Italian speakers. Sub collections may or may not share members among them.

A gufo:RelationshipType derived from intrinsic aspects of the related entities.

For example, "heavierThan", "olderThan".

For a gufo:ComparativeRelationshipType it is recommended to identify the types of intrinsic aspects from which it is derived (see gufo:isDerivedFrom). For example "heavierThan" is derived from the "Weight" quality type.

Note that, in the case of relationships that may change in different circumstances or times, the use of a qualified relation pattern enables indicating the period of time in which the relationship holds. See gufo:TemporaryRelationshipSituation.

Corresponds to "comparative formal relation" in Guizzardi (2005) and "Comparative Relation" in Fonseca et al. (2019).

A gufo:Individual that exists in space-time.

Concrete individuals comprise not only object-like entities (a car, a mountain, a person, a marriage, a belief), but also events (a business meeting, a soccer match) and situations (the situation in which a person weighs 80 kilograms, the situation in which a bank account is overdrawn).

A gufo:Type whose instances are concrete individuals.

Instances of gufo:ConcreteIndividualType are subclasses of gufo:ConcreteIndividual.

Examples include the gufo:Kind "Person", the gufo:Category "Physical Object", the gufo:EventType "Business Meeting".

A gufo:ConcreteIndividual that endures in time and may change qualitatively while keeping its identity.

Examples include: ordinary objects of everyday experience, such as a person, a house, and a car; reified relationships, such as a marriage, a rental contract, and a person's love for another; and existentially-dependent aspects of objects, such as a car's weight, a person's language skills, and a house's color.

Also termed "continuant" in the philosophical literature.

A gufo:Type whose instances are endurants.

Instances of gufo:EndurantType are subclasses of gufo:Endurant.

Examples include the object kind "Person", the phase "Child", the relator kind "Marriage".

See Guizzardi et al. (2018) for details concerning the taxonomy of endurant types included here.

A gufo:ConcreteIndividual that 'occurs' or 'happens' in time. They may be instantaneous or long-running. Events are those "things that happen to or are performed by" (Casati and Varzi, 2015) endurants.

Examples include actions and processes, such as a business meeting, a communicative act, a soccer match, a goal kick, the clicking of a mouse button; as well as natural occurrences such as an earthquake, the fall of the meteor that caused the extinction of the dinosaurs.

Also termed "happening", "occurrence", "perdurant" or "occurrent" in the philosophical literature.

Casati, R. & Varzi, A. (2015). Events. In E.N. Zalta (Ed.), The Stanford Encyclopedia of Philosophy (Winter 2015 ed.). 19 Metaphysics Research Lab, Stanford University. https://plato.stanford.edu/archives/win2015/entries/events/

A gufo:Type whose instances are events.

Instances of gufo:EventType are subclasses of gufo:Event.

Examples include "Business Meeting", "Birth", "Musical Performance".

A gufo:Aspect that depends on one or more concrete individuals.

Extrinsic (or "relational") aspects are reified relationships, e.g., John and Mary's marriage, Mary's employment contract at Nasa, or parts of those relationships, e.g., John's obligations towards Mary in the scope of the marriage, Mary's reciprocal claims, Mary's obligations towards John, John's reciprocal claims. Extrinsic aspects can also be reified one-sided relationships, e.g., John's admiration for Obama (which depends on Obama but does not characterize him).

Corresponds to "Extrinsic Moment" in Fonseca et al (2019). Encompasses "Externally Depedent Mode", "Qua Individual" and "Relator" in Guizzardi (2005).

A gufo:ExtrinsicAspect that inheres in a concrete individual and depends on others for its existence.

A gufo:ExtrinsicMode can be understood as a reified one-sided relationship, such as John's admiration for Mary.

Corresponds to "Extrinsic Moment" in Fonseca et al (2019). Encompasses what "Externally Dependent Mode", "Qua Individual" and "Relator" in Guizzardi (2005).

A gufo:Collection for which no change in membership is possible.

Such a collection obeys an extensional principle of identity, i.e., two fixed collections are the same if, and only if, they have the same members.

Consider, for example, a group of people understood as a gufo:FixedCollection. In this case, any change in the membership of the group (e.g., the addition of one person) would in fact create a different group of people. In this case, the gufo:FixedCollection may be contrasted with the complexes they constitute. For instance, The Beatles (the band conceived as a gufo:FunctionalComplex) was in a certain circumstance constituted by the collection {John, Paul, George, Pete} and in another one constituted by the collection {John, Paul, George, Ringo}. The replacement of Pete Best by Ringo Star does not alter the identity of the band, but creates a different group of people.

http://purl.org/nemo/gufo#isComponentOf

An entity that (unlike a gufo:Type) cannot be instantiated.

Individuals may be either concrete (e.g., the Earth, Mick Jagger, Brazil, the 1985 Mexico City Earthquake) or abstract (e.g., the number two, the proposition that 'three is a prime number').

Also known as "particular" in the philosophical literature.

A gufo:Aspect that depends on a single concrete individual in which it inheres.

Examples include intrinsic physical aspects, such as the Moon's mass, Lassie's fur color; the fragility of John Lennon's glasses; mental dispositions, such as Bob's math skills, his belief that the number one is odd.

A gufo:IntrinsicAspect is classified as a gufo:Quality (e.g., an apple's weight, the height of the Statue of Liberty) if it is measurable by a certain value space, or as a gufo:IntrinsicMode (e.g. Bob's belief that the Eiffel Tower is in Paris) otherwise.

Corresponds to "Instrinsic Moment" in Guizzardi (2005). Different from Guizzardi (2005), here we consider that aspects can inhere in concrete individuals in general, and not only in endurants.

A gufo:IntrinsicAspect that is not measurable.

For example, Bob's belief that the Eiffel Tower is in Paris, his math skills, his headache.

Corresponds to "Mode" in Guizzardi (2005).

A gufo:EndurantType that is both sortal and rigid. It provides a uniform principle of identity for its instances. Every gufo:Endurant instantiates one and only one gufo:Kind.

Examples include kinds of ordinary objects of everyday experience, such as: "Person", "House", "Car"; kinds of relators, such as "Marriage", "RentalContract"; kinds of existentially-dependent aspects of objects, such as "Weight", "Belief", "Vulnerability".

A gufo:RelationshipType derived from extrinsic aspects of the related entities.

For example, "marriedWith", "employedBy", "enrolledIn", "admires".

For a gufo:MaterialRelationshipType it is recommended to identify the type of extrinsic aspect from which the material relationship type is derived (see gufo:isDerivedFrom). For example "marriedWith" can be derived from the "Marriage" relator type, "employedBy" can be derived from the "Employment" relator type.

Encompasses "Material Relation" in Guizzardi (2005) and corresponds to "Material Relation" in Fonseca et al. (2019).

A gufo:EndurantType that is both non-sortal and semi-rigid. As a semi-rigid type, it applies necessarily to some of its instances and contingently to some others. As a non-sortal, it captures properties shared by instances of different kinds.

For example, the type "FemaleAnimal" may be considered a gufo:Mixin as it applies necessarily to animals of certain species, e.g., lions and sharks, while it applies contingently to animals of other species such as clownfish and mushroom corals (which may change sex given certain conditions).

A gufo:EndurantType that does not apply necessarily to at least one of its instances (see Guizzardi, 2005, chapter 4).

Examples include anti-rigid types, such as the role "Student" and the phase "Child", and semi-rigid types, such as the mixin "MusicalArtist" (which necessarily characterizes bands, but contingently characterizes people) and the mixin "FemaleAnimal" (which is necessarily characterizes female dogs, but contigently characterizes clownfish).

A gufo:EndurantType that applies to individuals of different kinds (see Guizzardi, 2005, chapter 4).

Non-sortals do not provide a uniform principle of identity for their instances; instead, they just classify things that share common properties but which obey different principles of identity.

Also termed "dispersive" types in the philosophical literature.

A gufo:Endurant that does not depend on another endurant for its existence (excluding its essential parts and aspects).

Examples of objects include ordinary physical entities, such as a dog, a house, a tomato, a car, Alan Turing, but also socially-defined entities such as The Rolling Stones, the European Union, the Brazilian 1988 Constitution.

Guizzardi (2005) also included the more abstract notion of "Substantial", which generalizes both objects and amounts of matter. That notion was left out from this implementation, together with the notion of amount of matter. Support for the representation of maximally-self-connected amounts of matter is given by gufo:Quantity.

A gufo:Event that depends on a single object.

Participations can be used to partition an event into portions, each of which depend exclusively on a single object. Consider a business meeting with multiple participants, including John and Mary. John's participation in the meeting encompasses all events that are part of the meeting and that depend solely on him. Likewise, Mary's participation encompasses all events that are part of the meeting and that depend solely on her. Similarly, in Brutus’ stabbing of Caesar, we may identify the participations of Brutus, of Caesar, and of the dagger.

A gufo:EndurantType that is both sortal and anti-rigid. It is defined by instrinsic but contingent instantiation conditions. Phases are relationally independent types that capturec instrinsic properties shared by instances of a given kind.

For example, "Child" may be considered a gufo:Phase as a subclass of the gufo:Kind "Person", instantiated by persons younger than 12. Another example is the type "IllPerson", which may be considered a gufo:Phase that is instantiated whenever an instance of "Disease" (a gufo:IntrinsicMode) inheres in a person.

A gufo:EndurantType that is both non-sortal and anti-rigid. It is defined by instrinsic but contingent instantiation conditions. Phase mixins are relationally independent types that capture instrinsic properties shared by instances of different kinds.

For example, "LivingAnimal" may be considered a gufo:PhaseMixin as a superclass of the phases "LivingPerson" (specializing the gufo:Kind "Person") and "LivingDog" (specializing the gufo:Kind "Dog").

A gufo:IntrinsicAspect that is measurable by some value spaces. A quality may be used to compare individuals, on the basis of the value it takes in a certain quality space (for instance, a position within the RGB spectrum).

Examples include the weight of a person, the name of organization, the color of a car, and the duration of a concert.

A gufo:AbstractIndividual that can be associated with a gufo:Quality reflecting the perception or conception of the quality in a certain value space.

Instances of gufo:QualityValue include the rational number 2.5 when used to conceive of the acidity of a portion of wine (in a pH scale), the tuple <38.8897,-77.0089> when used to conceive of the location of a building (in a space formed by latitude and longitude), or the triplet <0,0,0> when used to conceive of the color of a physical object (in a trimensional space formed by red, green and blue color components).

Corresponds to "Quale" in Guizzardi (2005).

Use this class only for quality values (qualia) that are to be reified in the A-box and associated with a gufo:ConcreteIndividual through the object property gufo:hasReifiedQualityValue. Otherwise, use the gufo:hasQualityValue data property and a literal to determine the quality value.

A gufo:Situation in which a quality value is temporarily attributed to a gufo:Endurant.

A gufo:QualityValueAttributionSituation should be used only for mutable qualities, i.e. those whose value can vary in time.

Examples include: the situation in which the value of a bitcoin in Euros is 6.526,12, which lasted from 10/12/2019 to 11/12/2019; the situation in which the weight of Mike Tyson was 100 kg; and the situation in which the color of Einstein' hair was grey.

This is a reification of the quality value attribution (in a solution that is similar to the qualified relation pattern http://patterns.dataincubator.org/book/qualified-relation.html )

A complex gufo:Object that is a maximally-connected portion of stuff. A gufo:Quantity has a fixed constitution, and thus, removing or adding a sub-quantity would result in a different quantity.

Examples include the portion of wine in a wine tank, a lump of clay, the gold that constitutes a wedding ring.

Also termed "quantity of matter", "objectified portion of matter", "piece" in the philosophical literature.

A gufo:Type whose instances are ordered pairs of related entities. Instances of gufo:RelationshipType are object properties in UFO-based ontologies.

The object properties "marriedWith" and "enrolledIn" are examples of material relationship types. The object properties "heavierThan", "olderThan" are examples of comparative relationship types.

The use of gufo:RelationshipType and its subclasses requires OWL 2 punning.

Corresponds to "Relation" in Guizzardi (2005) and Fonseca et al. (2019).

A gufo:ExtrinsicAspect that connects (involves, mediates) two or more concrete individuals. Relators are reified relationships composed of reciprocal extrinsic modes.

Examples of relators include John and Mary's marriage (composed of John's obligations towards Mary in the scope of the marriage, Mary's reciprocal claims, Mary's obligations towards John, John's reciprocal claims), Mary's employment contract at Nasa, a covalent bond between two atoms.

A gufo:EndurantType which applies necessarily to its instances (see Guizzardi, 2005, chapter 4).

Examples include the types "Agent", "Person", "Animal", "PhysicalObject", "Car", and "Tree".

A gufo:EndurantType that both sortal and anti-rigid. It is defined by relational instantiation conditions. Roles are relationally dependent types, capturing relational properties shared by instances of a given kind.

For example, "Student" may be considered a gufo:Role as a subclass of the gufo:Kind "Person", instantiated by all persons enrolled in a school. "

A gufo:EndurantType that is both non-sortal and anti-rigid. It is defined by relational instantiation conditions. Role mixins are relationally dependent types, capturing relational properties shared by instances of different kinds.

For example, "Customer" may be considered a gufo:RoleMixin as a superclass of the roles "CorporateCustomer" (specializing the gufo:Kind "BusinessOrganization") and "PersonalCustomer" (specializing the gufo:Kind "Person").

A gufo:NonRigidType that applies necessarily to some of its instances and contingently to some others (see Guizzardi, 2005, chapter 4).

A gufo:ConcreteIndividual that is a particular configuration of a part of reality which can be understood as a whole and in which entities stand in relations. A situation may be counterfactual or actual. An actual situation (or in other words, a "fact") "obtains" in a certain time instant or during a time interval.

Note that, in Guizzardi et al. (2013), situations were considered to obtain at a specific point in time. Here, instead, they obtain in a time interval when begin and end points differ.

The various subclasses of Situation in this implementation are used to capture "mutable" facts which obtain during some time and fail to obtain at other times. This includes the contingent instantiation of non-rigid types (e.g., as someone is a child at one point in time and a teenager later), the attribution of value to mutable qualities (such as a person's weight) and temporary participation in part-whole relations for replaceable parts (such as a car's tires). Other subclasses may be created to capture domain-specific notions such as "HazardousSituation", "PersonHasFever".

A gufo:Type whose instances are situations.

Instances of gufo:SituationType are subclasses of gufo:Situation.

Examples include "HazardousSituation", "PersonHasFever", "PersonIsStudent".

A gufo:EndurantType which carries (or supplies) a principle of identity for its instances (see Guizzardi, 2005, chapter 4).

A gufo:EndurantType that is both sortal and rigid. It specializes a gufo:Kind carrying the principle of identity supplied by that kind. Every gufo:SubKind should directly or indirectly specialize a gufo:Kind.

For example, the gufo:Kind "Lion" may be specialized into the "Lionness" and "Male Lion" subkinds, while the gufo:Kind "Computer" may be specialized into the "Laptop" and "Desktop" subkinds.

A gufo:Situation in which a gufo:Endurant temporarly constitutes another gufo:Endurant.

When constitution of an object may change in time, it may be qualified by the period in time in which the relation applies.

Examples include: the situation in which the Beatles is constituted by the group composed of {John,Paul,Ringo,George}; and the situation in which the statue of Venus de Milo was constituted by its original quantity of marble (including its arms).

This is a reification of constitution (in a solution that is similar to the qualified relation pattern http://patterns.dataincubator.org/book/qualified-relation.html)

A gufo:Situation in which a gufo:Endurant temporarily instantiates a gufo:NonRigidType.

A gufo:TemporaryInstantiationSituation can account for the time period in which a particular instantiation holds.

Examples include: the situation in which Obama instantiates the role of president, which began in 20/01/2009 and lasted until 20/01/2017; the situation in which Coatria instantiates the role of EU Member, which began in 01/07/2013 (and is still on-going); and the situation in which Steve Jobs instantiates the child phase, which began in 24/02/1955 and lasted until 24/02/1965.

This solution is inspired in the qualified relation pattern (http://patterns.dataincubator.org/book/qualified-relation.html).

A gufo:Situation in which a gufo:Endurant is temporarily a part of another gufo:Endurant.

A gufo:TemporaryParthoodSituation should only be used for mutable parts. It may be qualified by the period in time in which the relation applies.

Examples include: the situation in which the United Kingdom is a member of the European Union; the situation in which Messi is a a member of the Barcelona FC squad; the situation in which an engine is part of a car; and the situation in which a transplanted heart is part of a person.

Note that, since every instance of gufo:Quantity or gufo:FixedCollection only has essential parts, the gufo:TemporaryParthoodSituation should not be used to represent these parthood relations.

This solution is inspired in the qualified relation pattern (http://patterns.dataincubator.org/book/qualified-relation.html).

A gufo:Situation in which a gufo:Endurant temporarily stands in a relation with another gufo:Endurant (or other endurants in the case of n-ary relationships).

Reification of a gufo:TemporaryRelationshipSituation allows qualification of the relationship with the period in time in which it applies.

Examples include: the situation in which Einstein works at the Swiss Patent Office in Bern; the situation in which Elon Musk studies at the University of Pennsylvania; the situation in which John Lennon is married to Yoko Ono; and the situation in which Facebook has a lower market value than Amazon.

For material relationships, prefer the use of gufo:Relator.

This is a reification of the relationship (in a solution that is similar to the qualified relation pattern http://patterns.dataincubator.org/book/qualified-relation.html).

An entity that may be instantiated by (or predicated over) other entities. Types encompass what we often call "sorts", "kinds", "categories", etc.

Examples include the kind "Person", the event type "Earthquake", and the abstract individual type "NaturalNumber". Relations, such as "marriedTo" and "olderThan", are also considered as types.

Instances of gufo:Type are classes, and should specialize the taxonomy of individuals of gUFO. For example, "Person" is a gufo:Type (more specifically a gufo:Kind), specializing gufo:Object. The mechanism that allows for this is called punning in OWL 2.

Encompasses the notion of "Universal" in Guizzardi (2005).

A gufo:Collection for which change in membership is possible.

Such a collection obeys an intensional principle of identity, i.e., change in membership does not necessarily create a different collection.

For example, KLM's fleet of airplanes could be understood as a gufo:VariableCollection. In this case, when the company acquires (or retires) an airplane, the fleet changes. Note that, in this case, the airplanes are conceptualized as playing the role of "member of a fleet". If various roles for the parts of a fleet were envisioned (such as "cargo airplane", "passenger airplane"), then a fleet would be best understood as a gufo:FunctionalComplex.

See gufo:TemporaryParthoodSituation for the pattern to represent the relation of a variable collection to its temporary parts.

An gufo:AbstractIndividual that reifies time instants. It is used as a target of the gufo:hasBeginPoint and gufo:hasEndPoint object properties.