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Properties panels
The Main tab of the Class property panel is used to edit the main information about a class and its basic OWL axioms.
It contains the class name, the main comment field, and sections for class expressions and annotations.
The Name field contains the class name. This is the main identifier of the class in the ontology.
Example: Student
The Comment field represents the first class annotation assertion of type rdfs:comment.
It is used to store a human-readable description of the class. In OWL terms, this corresponds to an AnnotationAssertion axiom whose annotation property is rdfs:comment.
Example: MandatoryCourse has the comment:
"Mandatory courses are taught by only professors"
This corresponds to: AnnotationAssertion(rdfs:comment :MandatoryCourse "Mandatory courses are taught by only professors")
Each section below contains OWL axioms related to the selected class.
A new entry can be added by pressing the + button.
This section contains class expressions that are equivalent to the selected class.
Example: Professor is equivalent to:
Teacher and facultyLevel value Level_Professor
This means that a class member is a Professor exactly when it is a Teacher whose facultyLevel is Level_Professor.
This section contains superclass axioms of the selected class.
Example: Student has superclass:
:Person
It also has superclass restrictions:
exactly 1 enrolled value from AcademicProgram at least one takes value from Course
So, in OWLGrEd, the SuperClasses section for Student would include:
Personenrolled exactly 1 AcademicProgramtakes some Course
This section contains classes that are disjoint with the selected class.
Example:
MandatoryCourse is disjoint with OptionalCourse
This means that no individual can belong to both classes at the same time.
The Keys section is used to define HasKey axioms for the selected class.
A key specifies one or more properties that can be used to uniquely identify individuals of that class. In OWL, this corresponds to a HasKey axiom.
Example:
Person has key: personID
This corresponds to: HasKey(foaf:Person ( :personID ))
Keys dialog
The Keys dialog contains a table where each row represents one property included in the key.
It has the following columns:
- Property - the property used as part of the key
- IsInverse - specifies whether the inverse of the property is used
- Delete - removes the property from the key definition
The Add button inserts a new row, allowing another property to be included in the same key.
The dialog therefore allows a key to consist of one or several properties.
This section contains other annotations of the class.
These are annotation assertions attached to the class, such as labels, comments, notes, or other metadata.
Each annotation corresponds to an AnnotationAssertion axiom whose subject is the selected class.
Example:
annotation type: commentvalue: Mandatory courses are taught by only professorslanguage: en
This corresponds to an annotation assertion such as:
AnnotationAssertion(rdfs:comment :MandatoryCourse "Mandatory courses are taught by only professors"@en)
To create or edit an annotation, click the + button in the Annotation section. This opens the Annotation dialog.
Annotation dialog
The Annotation dialog contains the following fields:
- AnnotationType - the annotation property used for the annotation
- Value - the annotation value
- Language - the language tag of the annotation value
The Attributes tab is used to manage the attributes of the selected class.
Attributes represent datatype properties that are shown inside the class box in the diagram. They describe data values of class individuals, such as names, codes, numbers, or other literal values.
For example, in the class Course, the following attributes are shown:
courseCode : stringcourseCredit : (integer[> 0])courseName : string
The + button in the top-right corner is used to create a new attribute.
To create or edit an attribute, click the Edit button for an existing attribute or the + button in the Attributes tab. This opens the Attributes dialog.
The dialog is used to define one attribute of the selected class.
The Name field contains the attribute name.
Example:
courseCredit
This is the name shown in the class box and in the attribute list.
The Type field specifies the datatype of the attribute.
Examples:
string(integer[> 0])
The type may be:
- a simple datatype, such as
string, - or a restricted datatype expression, such as
(integer[> 0]).
The Multiplicity field is used to specify the allowed number of values for the attribute.
This field can be used when the attribute should have cardinality restrictions.
The Annotations section is used to add annotations for the attribute.
Each annotation row contains:
- Annotation Type
- Value
- Language
- Delete
The Add button inserts a new annotation row.
The Is Functional checkbox specifies whether the attribute is functional.
If selected, the attribute can have at most one value for each individual of the class.
The Equivalent Properties section is used to specify properties equivalent to this attribute.
If two properties are equivalent, they have the same meaning.
The Super Properties section is used to specify superproperties of the attribute.
This means that the current attribute is a subproperty of another property.
The Disjoint Properties section is used to specify properties that are disjoint with this attribute.
The Association dialog is used to edit an association between two classes. In OWL, an association corresponds to an object property and connects individuals of one class to individuals of another class.
In the diagram, one line represents both:
- the object property, shown in one direction, and
- its inverse object property, shown in the opposite direction.
For example, the association between Teacher and Course may be shown as:
teachesisTaughtBy
The dialog contains two tabs:
- Role – for the property in one direction
- InvRole – for the inverse property in the opposite direction
Both tabs have the same structure.
Each of these tabs is used to define one direction of the association.
The Name field contains the property name.
Example:
teaches
In the inverse tab, the name could be:
isTaughtBy
These names are shown on the association line in the diagram.
The Multiplicity field is used to specify the allowed number of related individuals for the property.
This field can be used to express cardinality restrictions for the corresponding role.
The EquivalentProperties section is used to specify object properties that are equivalent to the selected property.
If two object properties are equivalent, they express the same relationship.
The SuperProperties section is used to specify superproperties of the selected property.
This means that the current property is a subproperty of another object property.
The DisjointProperties section is used to specify object properties that are disjoint with the selected property.
If two object properties are disjoint, the same pair of individuals cannot be related by both properties.
The following checkboxes are used to define standard OWL object property characteristics:
- Functional - each subject can be related to at most one object through this property
- InverseFunctional - each object can be related to at most one subject through this property
-
Symmetric - if
xis related toy, thenyis related tox -
Asymmetric - if
xis related toy, thenycannot be related tox - Reflexive - every individual is related to itself
- Irreflexive - no individual is related to itself
-
Transitive - if
xis related toyandyis related toz, thenxis related toz
The PropertyChains section is used to define property chain axioms for the selected property.
A property chain states that a sequence of object properties implies the selected property.
The PropertyChains subdialog has the the following columns:
- Property - the property used as part of the property chain
- IsInverse - specifies whether the inverse of the property is used
- Delete - removes the property from the key definition
The Annotation section is used to add annotations to the selected property.
Annotations provide descriptive metadata such as comments, labels, or notes and do not affect logical reasoning.
The Annotation subdialog has the same structure as the class annotation dialog:
- AnnotationType
- Value
- Language