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Diff layers

owlcompare analyzes a change at four increasing levels of meaning. This page will document each layer in detail — what it detects, how it's implemented, and how the layers cooperate so that a higher layer's events subsume the lower-layer triples that caused them. It draws on the internal slice specs but is rewritten for comprehension rather than implementation. The overview places these layers in the full pipeline.

This page is being expanded

The outline below anchors the scope; the per-layer detail is coming.

What this page will cover

  • Layer 0 — Syntactic. The raw triple delta. Always computed, hidden when a higher layer explains it. The --show-syntactic escape hatch.
  • Layer 1 — Structural. The four slices:
    • Entities — classes and properties added, removed, deprecated.
    • Hierarchy — subClassOf / subPropertyOf edges and reparenting.
    • Restrictions — cardinality, value restrictions, domain/range.
    • Annotations — labels, comments, metadata.
  • Subsumption — how a Layer 1 event claims the Layer 0 triples behind it, and how the subsumption registry is recorded.
  • Layer 2 — Inferential (planned). Diffing entailed facts with a reasoner.
  • Layer 3 — Impact (planned). SHACL-shape and SPARQL-query impact analysis.
  • Why v1 ships 0 and 1 only — the deliberate scoping decision.