Graph Widget Tutorial OWL

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Graph Widget Tutorial for OWL Ontologies


This tutorial assumes a basic working knowledge of Protege-OWL.



What is the graph widget?

The graph widget is a custom property widget that serves as an alternative to Protege Forms for creating and/or populating individuals in Protege-OWL. It is particularly useful in the following scenarios:

  • visual editing of individuals and relationships between individuals
  • visualizing networks of individuals
  • visualizing relationships between individuals
  • speeding up knowledge acquisition in ontologies with heavily interconnected concepts
  • viewing data that resembles process diagrams, flow charts, organizational charts, etc.


A few words about Protege Forms

Before learning to use the graph widget, it is important to understand the concept of a Protege Form.

For each class in your ontology, Protege-OWL generates a default form that can be used to enter data for individual members of the class. Forms contain a data entry field, or "widget" for each property of an individual. There are different types of widgets to handle the various property types, e.g., Protege-OWL assigns a "MultiLiteralWidget" to datatype properties of type string, a "SingleLiteralWidget" for functional datatype properties of type string, etc.

If you do not like the property widgets that Protege-OWL assigns by default, you can customize individual forms on the Forms tab. Please note that the graph widget is only allowed for object properties that accept multiple values (non-functional).


Example ontology

For the purposes of this tutorial, we will use a simplified version of a clinical trial ontology developed by Ravi Shankar at BMIR. For the most part, the concepts in this ontology are self-explanatory. To follow are some definitions of class names that may be less obvious at first glance:

  • Aliquot – a measured portion of a sample taken for analysis
  • Assay – a laboratory test to find and measure the amount of a specific substance
  • Specimen_Protocol – protocol for handling a specimen in a clinical trial

In order to follow along with the tutorial in Protege-OWL, please download a copy of the example clinical trial ontology.