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Dul/World Model
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The World Model: Fundamental Categories

The Top-Level Ontology

DUL's root is Entity, defined as: "Anything: real, possible, or imaginary, which some modeller wants to talk about for some purpose."

This maximally permissive definition reflects DUL's pluralistic stance: if someone needs to model something, it qualifies as an Entity.

Direct subclasses of Entity:

Entity
├── Abstract          (not located in space-time)
├── Event             (temporal extent, participants)
├── InformationEntity (information: abstract or concrete)
├── Object            (spatial location)
├── Quality           (aspects of entities)
└── Situation         (contextualized views)

Abstract Entities

Abstract: Entities not located in space-time.

Key subclasses:

FormalEntity

  • Formally defined, context-independent, "Platonic" entities
  • Mathematical entities: sets, categories, functions
  • Distinguished from Concepts (which are social/context-dependent)
  • Example: The mathematical set ℕ (natural numbers)

Region

  • Values in dimensional spaces
  • Subclasses represent different dimensions:
    • SpaceRegion: Spatial coordinates, geometries
    • TimeInterval: Temporal extents
    • Amount: Quantities (mass, volume, count)
    • PhysicalAttribute: Physical measurements (temperature, pressure)
    • SocialObjectAttribute: Social attributes (salary level, legal status)

Why Regions are Abstract:

  • The number "42" exists independently of any particular 42 objects
  • The color "red" exists independently of any particular red object
  • They inhabit abstract dimensional spaces, not physical space-time

Objects

Object: Entities with spatial location, participating in events.

The Physical vs. Social Divide

DUL makes PhysicalObject and SocialObject disjoint—a fundamental ontological distinction:

PhysicalObject

  • Has spatial region
  • Has (typically) mass
  • Exists independently of communication

Subclasses:

  • PhysicalBody: Natural material objects
    • BiologicalObject: Living organisms
    • ChemicalObject: Chemical substances
    • Substance: Materials (water, steel, DNA)
  • PhysicalArtifact: Human-made physical objects
    • DesignedArtifact: Artifacts with explicit design (cars, buildings)
  • PhysicalPlace: Locations understood as physical regions

SocialObject

  • Exists through communication (in "some communication Event")
  • Must be expressed by InformationObject
  • Disjoint from PhysicalObject

Subclasses:

  • Description: Conceptual schemas (theories, frames)
    • Plan, Design, Diagnosis, Norm, Contract, Goal, Theory, Narrative
  • Concept: Categories defined in descriptions
    • Role, Task, EventType, Parameter
  • Collection: Containers for entities sharing properties
    • Configuration, Collective, TypeCollection
  • InformationObject: Abstract information pieces
  • Place: Socially constructed locations (countries, neighborhoods)

Agent (Cross-cutting)

A special Object category for entities with agency:

  • PhysicalAgent: Biological agents (organisms, persons as physical beings)
  • SocialAgent: Socially constructed agents
    • Organization: Structured institutions (companies, governments)
    • CollectiveAgent: Groups acting collectively
      • Group: Coordinated collectives (committees, teams)
      • Community: Large-scale collectives (societies, movements)

Person is modeled with two facets:

  • NaturalPerson: The physical/biological aspect (extends Person and PhysicalAgent)
  • SocialPerson: The social/legal aspect (extends Person)

This dual modeling reflects that a person is both a physical organism and a social entity with roles, rights, and legal status.

Events

Event: "Any physical, social, or mental process, event, or state."

DUL's Aspectual Neutrality

The Event class documentation provides extensive philosophical discussion:

The Problem: The same real-world occurrence can be viewed as:

  • An accomplishment (process leading to a result)
  • An achievement (the result state)
  • A punctual event (time-collapsed)
  • A transition (change between states)

DUL's Solution: Don't classify Events by aspect—use Situations for aspectual views:

  • The Event "rock erosion in Sinni valley" has a single identity
  • ErosionAsAccomplishment: A Situation viewing it as a process
  • ErosionAsTransition: A Situation viewing it as a state change
  • Both Situations include the same Event but satisfy different Descriptions (theories of aspect)

Subclasses:

Action

  • Event with at least one Agent participant
  • Executes a Task typically defined in a Plan
  • Intentional, goal-directed

Process

  • Event without agentive focus
  • Natural or social processes (erosion, inflation, aging)

State (implied but not always distinguished)

  • Stative events (being tall, being red)

Qualities

Quality: Individual aspects of entities that cannot exist independently.

Examples:

  • The specific yellowness of Dmitri's skin (not yellowness in general)
  • The specific height of this building (not 180cm in general)
  • The specific beauty of this painting

Key relations:

  • isQualityOf: Links quality to its bearer (entity)
  • hasRegion: Links quality to its value (region)

When to use Qualities: DUL advises using Qualities only when individual aspects matter:

  • Relevant: Antique furniture appraisal (each piece's individual patina, color, texture)
  • Irrelevant: Assembly line quality control (only conformance to design parameters matters)

For most domains, direct attributes suffice. Qualities enable:

  • Fine-grained observation modeling
  • Temporal change tracking (same quality, different regions over time)
  • Multi-perspective measurement (same quality, different parameters)

Situations

Situation: "A view, consistent with a Description, on a set of entities."

Dual Nature:

  1. Epistemological: A framed interpretation of reality

    • Created by observers applying conceptual frames
    • Multiple Situations can include the same entities (different framings)

  2. Technical: Reified n-ary relations

    • Binary relations project from Situations via isSettingFor
    • Enables time-indexing and parameter-based relations

Key Subclasses:

TimeIndexedRelation

  • Situations specifically for temporal context
  • Classification: Time-indexed concept-entity classification
  • Parthood: Time-indexed part-whole relations

PlanExecution

  • Situation of executing a Plan
  • Links Actions to Tasks, Agents to Roles

WorkflowExecution

  • Situation of executing a Workflow
  • Temporal sequencing of tasks

Transition

  • Situation of change between states

InformationEntity

InformationEntity: A catchall for information, abstract or concrete.

Motivation: Bypass ambiguities in ordinary language:

  • "The 3rd Gymnopedie" could mean the composition (abstract) or a particular recording (concrete)
  • InformationEntity covers both, allowing underspecification when convenient

Subclasses:

  • InformationObject (Abstract): The information content
  • InformationRealization (Concrete): Physical/event realization

Relation: realizes connects realization to object

ObjectAggregate

ObjectAggregate: Aggregates of distributed objects from a Collection.

Distinction:

  • Collection: First-order entity (a social object unifying members conceptually)
  • ObjectAggregate: The distributed physical aggregate of members
  • Set: Second-order formal entity (abstract set in mathematical sense)

Example:

  • Collection: "The Louvre Egyptian collection" (institutional concept)
  • ObjectAggregate: The physical artifacts distributed in display cases
  • Set: The mathematical set {artifact₁, artifact₂, ...}