feat: add ontology validation script for mobilityDCAT-AP serialisation files

[Daham-Mustaf]

Context

The validation repository currently validates RDF data against SHACL shapes.
A separate validation concern exists: validating the mobilityDCAT-AP ontology
serialisation files themselves (mobilitydcat-ap_v1.1.0.ttl, .rdf, .jsonld)
for internal consistency and correctness.

Problem

The ontology files have accumulated bugs (tracked in mobilityDCAT-AP/mobilityDCAT-AP#179)
that were only discovered through manual audit. There is currently no automated
way to catch these.

Possible validation approaches

1. OWL consistency check
Load the ontology into a reasoner (e.g. HermiT via owlready2, or ELK) and check
for logical inconsistencies — unsatisfiable classes, contradictory axioms etc.

2. SHACL shapes on the ontology itself
Write SHACL shapes that validate the ontology as data — e.g. every
owl:ObjectProperty must have dcam:domainIncludes, every owl:Class must
have rdfs:label and skos:scopeNote, every mobilitydcatap: term must use
https:// namespace etc.

3. RDF syntax validation
Parse all three serialisation files (TTL, RDF/XML, JSON-LD) and verify they
are syntactically valid and produce identical graphs.

4. Namespace consistency check
Script that scans all three files and flags any occurrence of
http://w3id.org/mobilitydcat-ap (wrong) vs https://w3id.org/mobilitydcat-ap.

5. Cross-serialisation consistency check
Load TTL, RDF and JSON-LD into separate graphs and compare — all three should
produce the same triples.

6. Download and validate from main repo
Script that downloads the current ontology files directly from the
mobilityDCAT-AP GitHub repository and runs all checks, enabling CI integration.

Proposed deliverable

A script scripts/validate_ontology.py that:

• Downloads the three serialisation files from the main repo (or accepts local paths)
• Runs syntax validation on all three
• Checks namespace consistency
• Compares triple counts across serialisations
• Optionally runs SHACL shapes on the ontology as data

Related

• fix: multiple bugs in mobilitydcat-ap_v1.1.0.ttl — namespace, version metadata, duplicate declarations mobilityDCAT-AP#179 — bugs found in manual audit
• fix(ontology): audit and correct mobilitydcat-ap_v1.1.0.ttl serialisation files mobilityDCAT-AP#180 — PR fixing those bugs
• fix(shacl): complete SHACL 1.1.0 validation extending DCAT-AP 2.0.1 V2 mobilityDCAT-AP#178 — SHACL shapes PR