Python API

API reference

Public classes for consistency checking and direct class hierarchy. HermitPy reads an rdflib graph and does not need a JVM.

hermitpy

Reasoner

Classify one ontology. Construct it from an rdflib.graph.Graph already parsed from Turtle, RDF/XML, or another format rdflib accepts.

Reasoner(graph: Graph)

Method	Returns	Purpose
`is_consistent()`	`bool`	Whether the ontology has a model.
`unsatisfiable_classes()`	`list[str]`	Named class IRIs that are empty in every model. If the ontology is inconsistent, every named class is returned.
`direct_subclasses()`	`list[tuple[str, str]]`	Direct `(subclass, superclass)` IRI pairs. Equivalent classes appear in both directions. Satisfiable classes with no stricter named parent link to `owl:Thing`. Unsatisfiable classes link to `owl:Nothing`.

from rdflib import Graph
from hermitpy import Reasoner

graph = Graph()
graph.parse("ontology.ttl")
reasoner = Reasoner(graph)

if reasoner.is_consistent():
    for child, parent in reasoner.direct_subclasses():
        print(child, "rdfs:subClassOf", parent)

rdflib.GraphNo JVM View source →

hermitpy

Errors

Exception	When
`UnsupportedConstruct`	The graph uses OWL outside the fragment, including datatypes, cardinality, property chains, nominals, role hierarchies, keys, and SWRL. The construct is named on the exception and is not ignored.
`InconsistentOntology`	`direct_subclasses()` was called on an ontology with no model.
`ReasonerLimitExceeded`	The tableau exceeded its node or search-depth bound.

from hermitpy import InconsistentOntology, UnsupportedConstruct

try:
    pairs = reasoner.direct_subclasses()
except InconsistentOntology:
    print(reasoner.unsatisfiable_classes())
except UnsupportedConstruct as error:
    print(error.construct)

View source →

OWL fragment

What the reasoner accepts

Accepted	Raises `UnsupportedConstruct`
Named classes, `owl:Thing`, `owl:Nothing`, subclass, equivalence, disjointness, complement, intersection, union, existential and universal restrictions on object and datatype properties, numeric datatype bounds, inverses, transitive and symmetric object properties, domain, range, class assertions, object-property assertions, and literal assertions.	Cardinality, property chains, `owl:oneOf`, role inclusion, keys, `owl:sameAs`, and SWRL.

direct_subclasses() refuses an inconsistent ontology. It does not classify every class as a subclass of owl:Nothing.