rustdl 0.3.0

Sound, performant OWL 2 DL (SROIQ) reasoner in Rust — Python bindings

rustdl

Sound, performant OWL 2 DL (SROIQ) reasoner in Rust, with Python bindings. No JVM, no subprocess — native classification via PyO3.

rustdl beats HermiT on every measured ORE workload and wins outright against Konclude on Horn-fragment ontologies. See the project README for the full benchmark table.

Install

pip install rustdl

Wheels are published for CPython 3.10+ on Linux (x86_64, aarch64), macOS (Apple Silicon), and Windows (AMD64). Other platforms build from the sdist (needs a Rust toolchain).

Quick start

import rustdl

# Classify an ontology. Format auto-detected from the extension:
# .ofn (OWL Functional), .owx (OWL/XML), .rdf / .owl (RDF/XML).
result = rustdl.classify("pizza.ofn")

print(f"{len(result.classes)} classes, {len(result.unsatisfiable)} unsatisfiable")

# Query the computed hierarchy
result.is_subclass("http://ex.org/Margherita", "http://ex.org/Pizza")  # -> bool
result.subclasses_of("http://ex.org/Pizza")     # -> list[str]
result.superclasses_of("http://ex.org/Margherita")  # -> list[str]
result.equivalent_classes("http://ex.org/Pizza")    # -> list[str]
result.direct_subsumers("http://ex.org/Margherita") # -> list[str] (Hasse-direct parents)

API

Classification

result = rustdl.classify(path, *, per_pair_timeout_ms=1000, saturation_only=False)
result = rustdl.classify_bytes(data, format="ofn", *, per_pair_timeout_ms=1000, saturation_only=False)

• per_pair_timeout_ms — bound each subsumption test (default 1000; 0 = unbounded). A pair that exceeds the budget is recorded as "not subsumed": sound (never a false subsumption) but the result may be incomplete. When that happens, an IncompleteClassificationWarning is emitted and result.complete is False. Pass 0 for the complete, unbounded classification. The default bounds pathological SROIQ inputs so classification can't hang silently.
• saturation_only — skip the tableau entirely; EL-closure-only under-approximation. Dramatically faster on mostly-EL ontologies, and always complete (no tableau ⇒ no timeout).

classify / classify_bytes return a Classification:

member	type	meaning
.classes	list[str]	all declared class IRIs
.unsatisfiable	list[str]	classes proved ⊑ ⊥
.inconsistent	bool	whole ontology unsatisfiable
.complete	bool	False if any pair hit the timeout (result may miss edges)
.timed_out_pairs	int	how many pairs hit the timeout
.is_subclass(sub, sup)	bool	is sub ⊑ sup entailed?
.subclasses_of(cls)	list[str]	every D with D ⊑ cls
.superclasses_of(cls)	list[str]	every D with cls ⊑ D
.equivalent_classes(cls)	list[str]	classes equivalent to cls
.direct_subsumers(cls)	list[str]	Hasse-direct parents of cls

One-shot queries

Each parses the file, answers one question, and returns:

rustdl.is_consistent(path)                        # -> bool
rustdl.is_class_satisfiable(path, class_iri)      # -> bool
rustdl.is_subclass_of(path, sub_iri, sup_iri)     # -> bool
rustdl.is_instance_of(path, class_iri, indiv_iri) # -> bool
rustdl.instances_of(path, class_iri)              # -> list[str]
rustdl.realize(path)                              # -> dict[str, list[str]]

realize returns each individual IRI mapped to its most-specific entailed class IRIs.

For repeated queries over the same ontology, prefer classify(path) once and query the returned Classification — each top-level function re-parses.

Inference materialization

rustdl.materialize_inferred_subclass_axioms(path)   # -> list[tuple[str, str]]
rustdl.materialize_inferred_class_assertions(path)  # -> list[tuple[str, str]]

materialize_inferred_subclass_axioms yields (sub, sup) pairs for every entailed subsumption (excluding reflexive, owl:Thing/owl:Nothing, and unsatisfiable classes). materialize_inferred_class_assertions yields (class, individual) pairs. Useful for writing an inferred ontology back to disk.

Errors

rustdl.RustdlError            # base — catches everything from the library
rustdl.ParseError             # the OWL file couldn't be parsed
rustdl.UnsupportedAxiomError  # HasKey, role chains > length 2, etc.
rustdl.UnknownClassError      # an IRI argument isn't a declared class

try:
    result = rustdl.classify("ontology.ofn")
except rustdl.ParseError as e:
    print(f"bad input: {e}")
except rustdl.RustdlError as e:
    print(f"reasoning failed: {e}")

Soundness & coverage

rustdl is sound: every reported subsumption is a genuine entailment (FP=0 against Konclude on the validation corpus). Completeness is partial — the default classifier is empirically near-complete across the measured corpus but not provably complete on all of SROIQ. saturation_only and per_pair_timeout_ms are sound-but-incomplete by construction.

Data-property and datatype axioms outside the recognized preprocessing patterns are silently dropped (a sound under-approximation). HasKey and role chains longer than length 2 raise UnsupportedAxiomError. SWRL rules are skipped.

See the project documentation for the full coverage matrix, soundness contract, and architecture notes.

License

Apache-2.0 OR MIT.