Author with Cypher¶

Projections are graphs all the way down, so Cypher writes are the editing model — for migrations, bulk edits, or building ontologies from scratch.

The contract¶

For a complete, serializable ontology, an authored graph should have:

• exactly one parentless node with kind: 'Ontology'
• every non-root node reachable from it through :E edges
• sibling edges carry distinct position values (child order)
• node properties match what the element kind allows (see The Graph Schema)

to_owlxml() requires exactly one parentless Ontology node and rejects dangling edge references, reachable cycles, and duplicate reachable sibling positions. It does not reject unreachable nodes, multiply parented nodes, or property/kind mismatches, so authoring code must avoid those conditions. role values on edges are optional decoration; only position matters for serialization.

Example: build a tiny ontology from nothing¶

from ontoplexis import Ontology, WritableProjection

wp = WritableProjection.open("authored.lbug")
wp.execute("CREATE (:N {uid: 'o', kind: 'Ontology', ontology_iri: 'http://example.org/x'})")
wp.execute("CREATE (:N {uid: 'd', kind: 'Declaration'})")
wp.execute("CREATE (:N {uid: 'c', kind: 'Class', iri: 'http://example.org/x#A'})")
wp.execute(
    "MATCH (o:N {uid:'o'}), (d:N {uid:'d'}) "
    "CREATE (o)-[:E {position: 0, role: 'axiom'}]->(d)"
)
wp.execute(
    "MATCH (d:N {uid:'d'}), (c:N {uid:'c'}) "
    "CREATE (d)-[:E {position: 0, role: 'entity'}]->(c)"
)
proj = wp.reopen_readonly()

ont = Ontology.from_projection(proj)
print(ont.to_owlxml())

Validation¶

Two layers catch mistakes:

1. Structure — serialize_owlxml (called by to_owlxml) rejects graphs with no root, multiple roots, reachable cycles, dangling edges, or duplicate reachable sibling positions, with a precise error.
2. OWL/XML parsing — parse the serialized document with an external OWLAPI-based tool such as robot convert.
3. Reasoning — use robot reason with an appropriate reasoner when you need a consistency or entailment check. Ontoplexis does not provide a separate semantic rule engine.