Taxonomic narrowing

classify:taxonomic-narrowing runs sequentially after the parallel classifier placement. It reads every other classifier's proposal and drops any supertype proposals when a more-specific subtype is also present. Result: when classify:rules proposes Weapon and classify:structural proposes Sword, only Sword survives — provided the TBox declares Sword rdfs:subClassOf Weapon.

It never adds class proposals; it only removes them. A __narrowing_applied__ sentinel summarises the audit trail for evidence preservation.

Config slot

Under classification.taxonomicNarrowing:

{
  "classification": {
    "taxonomicNarrowing": {
      "tboxFrom": "ontology",
      "enabled":  true
    }
  }
}

Field	Type	Required	Default	Notes
tboxFrom	string	yes		Either "ontology" (reads from plugin-provided services.ontology.tbox(); disables itself silently when null) or a filesystem path to a Turtle / N-Quads OWL TBox file (resolved relative to schemasBase).
enabled	boolean	no	true	When false, the node is a no-op.

TBox sources

tboxFrom value	Source
"ontology"	services.ontology.tbox() — uses the plugin-provided ontology. When null (no plugin provides one), the node disables itself silently.
any other path	Filesystem file. Format inferred from extension (.nq / .n-quads → N-Quads; everything else → Turtle). Loaded synchronously at construction.

Closure algorithm

1. Collect every <sub> owl:subClassOf <sup> quad where both terms are NamedNode. Class names are the IRI's last #-fragment or /-segment.
2. Seed closure[A] = directSupertypes[A].
3. Iterate until fixpoint: for each A, add every supertype-of-a-supertype reachable through the graph. Warshall-style; cycles terminate because the loop only adds, never removes.

The resulting Map<className, Set<supertypeName>> is cached in the node instance. Per-record execution reads state.proposals, identifies classes that another proposal supersedes, deletes those proposal slots, and writes a single __narrowing_applied__ sentinel under state.proposals['classify:taxonomic-narrowing']:

{
  "source":     "classify:taxonomic-narrowing",
  "className":  "__narrowing_applied__",
  "priority":   0,
  "confidence": 1,
  "reasons": [
    "narrowed: Sword subClassOf Weapon; dropped Weapon"
  ]
}

classify-conflict filters the sentinel before picking a winner; it surfaces in state.classification.reasons only when conflict.evidence: true.

Edge cases

• No subClassOf assertions. Closure is empty; the node returns no-op for every record.
• Cycles in subClassOf. Tolerated (the algorithm only adds entries, so it terminates). All classes in a cycle become mutually supertypes; every proposal is considered a supertype of every other; nothing survives. Don't ship cyclic TBoxes.
• Single proposal. Fewer than two proposals → nothing to narrow → no-op.

See also

• Classifier cascade
• Ontology (json-tology) — wire an ontology so tboxFrom: 'ontology' resolves.