Ontology Explorer

Goal

Enable an agent to understand, navigate, and query the structure of materials science ontologies without loading verbose OWL/XML files directly. Provides fast access to class hierarchies, property definitions, and domain-range relationships through pre-processed JSON summaries.

Requirements

• Python 3.8+
• No external dependencies (Python standard library only)
• Internet access required only for

  owl_parser.py

  and

  ontology_summarizer.py

  when fetching remote OWL files

Inputs to Gather

cmso

Material

UnitCell

hasMaterial

hasSpaceGroupNumber

crystal

lattice

https://raw.githubusercontent.com/OCDO/cmso/main/cmso.owl

Decision Guidance

What do you need?
├── Understand overall ontology structure
│   └── class_browser.py --ontology cmso --list-roots
├── Inspect a specific class
│   └── class_browser.py --ontology cmso --class <name>
├── Find properties for a class
│   └── property_lookup.py --ontology cmso --class <name>
├── Look up a specific property
│   └── property_lookup.py --ontology cmso --property <name>
├── Search for a concept
│   ├── class_browser.py --ontology cmso --search <term>
│   └── property_lookup.py --ontology cmso --search <term>
├── Parse a new/updated OWL file
│   └── owl_parser.py --source <path-or-url>
└── Generate/refresh a summary JSON
    └── ontology_summarizer.py --source <url> --output <path>

Script Outputs (JSON Fields)

scripts/owl_parser.py

results.metadata

results.classes

results.object_properties

results.data_properties

results.class_hierarchy

scripts/ontology_summarizer.py

results.output_file

results.statistics

scripts/class_browser.py

results.class_info

results.subtree

results.properties

results.path_to_root

results.roots

results.search_results

scripts/property_lookup.py

results.property_info

results.class_properties

results.search_results

Workflow

1. Identify which ontology the user is working with (default: CMSO).
2. Use

   class_browser.py --list-roots

   to see the top-level concepts.
3. Drill into specific classes with

   class_browser.py --class <name>

   to see hierarchy, children, and applicable properties.
4. Look up individual properties with

   property_lookup.py --property <name>

   .
5. If the user mentions a concept but not its ontology name, use

   --search

   to find matching classes or properties.
6. For a new or updated ontology, run

   owl_parser.py

   to parse the raw OWL, then

   ontology_summarizer.py

   to generate a summary JSON.

Conversational Workflow Example

User: I have an FCC copper simulation. What CMSO classes should I use to describe it?

Agent: Let me explore the CMSO ontology to find the relevant classes.

[Runs: class_browser.py --ontology cmso --search "crystal" --json]

For an FCC copper simulation, the relevant CMSO classes are:

- **Computational Sample** → **Atomic Scale Sample**: your simulation is an atomic-scale sample
- **Material** → **Crystalline Material**: copper is crystalline
- **Crystal Structure**: describes the FCC arrangement
- **Unit Cell**: the repeating FCC unit cell (a=b=c=3.615 Å, α=β=γ=90°)
- **Space Group**: FCC copper is space group 225 (Fm-3m)
- **Chemical Element**: Cu

The key relationships:
  AtomicScaleSample → hasMaterial → CrystallineMaterial → hasStructure → CrystalStructure → hasUnitCell → UnitCell

Shall I look up the specific properties for any of these classes?

CLI Examples

# List root classes in CMSO
python3 skills/ontology/ontology-explorer/scripts/class_browser.py \
  --ontology cmso --list-roots --json

# Inspect the Material class hierarchy
python3 skills/ontology/ontology-explorer/scripts/class_browser.py \
  --ontology cmso --class Material --json

# Search for crystal-related classes
python3 skills/ontology/ontology-explorer/scripts/class_browser.py \
  --ontology cmso --search crystal --json

# Find all properties for UnitCell
python3 skills/ontology/ontology-explorer/scripts/property_lookup.py \
  --ontology cmso --class UnitCell --json

# Look up a specific property
python3 skills/ontology/ontology-explorer/scripts/property_lookup.py \
  --ontology cmso --property "has space group" --json

# Parse a remote OWL file
python3 skills/ontology/ontology-explorer/scripts/owl_parser.py \
  --source https://raw.githubusercontent.com/OCDO/cmso/main/cmso.owl --json

# Generate a summary JSON from an OWL file
python3 skills/ontology/ontology-explorer/scripts/ontology_summarizer.py \
  --source https://raw.githubusercontent.com/OCDO/cmso/main/cmso.owl \
  --output summary.json --json

Error Handling

Ontology 'X' not in registry

references/ontology_registry.json

Class 'X' not found

--search

--list-roots

Property 'X' not found

--search

Cannot parse OWL source

Summary file not found

ontology_summarizer.py

Interpretation Guidance

• Class hierarchy: root classes are the broadest concepts; leaf classes are the most specific. A class inherits all properties from its ancestors.
• Object properties: show how classes relate to each other (domain → range). A property with domain

  UnitCell

  and range

  Basis

  means a unit cell has a basis.
• Data properties: show what literal values a class carries. A property with domain

  ChemicalElement

  and range

  xsd:string

  means an element has a string-valued attribute.
• Union domains: some properties apply to multiple classes (e.g.,

  hasVector

  applies to both

  SimulationCell

  and

  UnitCell

  ), shown as

  SimulationCell | UnitCell

  .
• Search relevance: 1.0 = label match, 0.5 = description match only.

Limitations

• Only supports OWL/XML format (not Turtle, JSON-LD, or N-Triples)
• Does not support OWL reasoning or inference (e.g., does not compute transitive closures)
• Class hierarchy extraction handles simple

  rdfs:subClassOf

  only (not complex OWL restrictions)
• Descriptions may be missing for classes that lack

  rdfs:comment

  ,

  skos:definition

  , or IAO annotations
• URL fetching requires internet access and may time out (30-second limit)

References

• OWL/RDF Primer — brief introduction to OWL concepts
• CMSO Guide — narrative guide to the CMSO ontology
• Ontology Registry — registered ontologies and their metadata
• CMSO Summary — pre-processed CMSO structure
• CMSO Documentation — official CMSO docs
• CMSO Repository — source OWL file and development

Version History