ontor

• What it is — ontor (ONTology editOR) is a Python library built on Owlready2 for creating, editing, extending, debugging, visualizing, and reasoning over OWL2 ontologies. Each ontor instance represents one ontology.

• Key concepts —

  • Ontologies contain taxonomies, classes, object and data properties, individuals/instances, relations, restrictions, and axioms.
  • General Class Axioms express statements more complex than ordinary class axioms; ontor implements them through equivalent helper classes as an Owlready2 workaround. The documented seafood-pizza example shows a reasoner inferring a price for matching classes and instances without requiring an explicitly defined class for that concept.
  • Ontologies can import other ontologies, and deletion can preserve structure by appropriately reassigning subclasses and instances.

• How you’d use it — Install with pip install ontor, then create or load an ontology, edit it through ontor’s tuple-based syntax, and save it; JSON and CSV are supported. The documented scratch workflow is add_taxo first, then add_ops/add_dps, followed by add_axioms/add_gcas/add_instances. You can extract axioms and class restrictions, run reasoning, interactively debug by deleting problematic axioms, and visualize selected classes, instances, and properties around a focus node.

• LLM angle — none stated

• Pitfalls & lessons — Creation order matters: the taxonomy must exist before properties, and properties before axioms or instances, because later steps depend on already-defined classes and properties. General Class Axioms require an equivalent-helper-class workaround in Owlready2.

• Verdict — A focused Owlready2-based editor for programmatic OWL2 ontology construction and maintenance, with structured import formats plus reasoning, debugging, and visualization support.

Sources consulted

• README.md
• docs/source/index.rst