OWL Diagram Notation
Introduction
This page describes the graphical notation for ontology diagrams generated by owl-cli. There is no standard diagram notation for OWL, but a number of tools provide their own notation. Popular options are the Protégé plugins OWLViz and OntoGraf, as well as the graphical notation of Topbraid Composer. Most notations have a strong focus on class and instance relationships, which is well-suited for visualizing this particular kind of ontology. However, other types of axioms, in particular more complex class expressions, are usually not represented. For this reason, during the writing of the PhD thesis, a more general graphical notation for ontologies was developed.
The notation by owl-cli is influenced by the following other notations for OWL ontologies:
-
The symbols and colors for classes, properties and data types as popularized by the Protégé ontology editor and also used by Topbraid Composer.
-
The notation from the PhD thesis (as shown on pages 43 and 44), but with less focus on Description Logics notation and instead using the expressions syntax from Protégé.
-
Arrows from UML (hollow arrow for inheritance, solid arrow for relations).
-
Representation of OWL class restrictions and other elements in the specification of the OMG Ontology Definition Metamodel 1.1, cf. for example Figures 14.25, 14.26 and 14.27.
-
The symbol for disjoint unions that is used in VOWL.
The notation was designed with the following goals in mind:
-
It must be possible to represent all OWL axioms in a meaningful way.
-
The diagrams are used mainly for visualizing in documents, not necessarily for interactively editing an ontology.
-
The diagram should be understandable for people familiar with the Protégé editor, because it is probably the most popular ontology editor.
-
The semantics should be unambiguous from the visual representation: For example, using a UML-like class diagram for an OWL class that includes properties in its box like class attributes in UML is not self-explanatory: Are the properties restrictions on the class (existential? universal? both?), is the class the domain of the properties? Both have very different meanings than what a UML-like representation suggests.
The following sections describe the graphical notation using examples.
All diagrams on this page were generated with owl-cli. Each diagram links to the RDF/Turtle file it was generated from. |
Data Ranges
This section is aligned to the corresponding section in the OWL 2 Specification. |
OWL Expression | Description Logics Notation | Diagram |
---|---|---|
|
||
DataUnionOf( ) |
|
|
|
||
DataOneOf( ) |
|
|
DatatypeRestriction( int minExclusive 4 maxInclusive 10 ) |
no notation |
Class Expressions
The outline of this section is aligned to the corresponding section in the OWL 2 Specification. |
Propositional Connectives and Enumeration of Individuals
OWL Expression | Description Logics Notation | Diagram |
---|---|---|
|
||
|
||
|
||
ObjectOneOf( ) |
|
Object Property Restrictions
OWL Expression | Description Logics Notation | Diagram |
---|---|---|
|
||
|
||
|
||
|
||
|
Object Property Cardinality Restrictions
OWL Expression | Description Logics Notation | Diagram |
---|---|---|
|
||
|
||
|
||
|
||
|
||
|
Data Property Restrictions
OWL Expression | Description Logics Notation | Diagram |
---|---|---|
|
||
|
||
DataHasValue( ) |
|
Axioms
The outline of this section is aligned to the corresponding section in the OWL 2 Specification. |
Class Expression Axioms
OWL Axiom | Description Logics Notation | Diagram |
---|---|---|
SubClassOf( ) |
|
|
|
||
|
||
|
Object Property Axioms
OWL Axiom | Description Logics Notation | Diagram |
---|---|---|
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
Data Property Axioms
OWL Axiom | Description Logics Notation | Diagram |
---|---|---|
|
||
|
||
|
||
|
||
|
||
|
Datatype Definitions
OWL Axiom | Description Logics Notation | Diagram |
---|---|---|
no notation |
Keys
OWL Axiom | Description Logics Notation | Diagram |
---|---|---|
HasKeys( ) |
no notation |
SWRL Rules
Rules defined in the Semantic Web Rule Language (SWRL) can be embedded in an OWL ontology. Rules are rendered as described in Human Readable Syntax, and are linked with the ontology entities they refer to. The following table shows rendering examples for the different kinds of rule atoms.
Atom Type | Diagram |
---|---|
Class |
|
Class with Expression |
|
Object Property |
|
Data Property, Data Range |
|
Data Property, Builtin |