Lab: Even More OWL
Lab 12: Even more OWL
Topics
OWL ontology programming with owlready2.
Classes and methods
In an earlier lab, you have already used these OWL concepts:
- (sameAs, equivalentClass, equivalentProperty, differentFrom, disjointWith, inverseOf)
- (ReflexiveProperty, IrreflexiveProperty, SymmetricProperty, AsymmetricProperty, TransitiveProperty, FunctionalProperty, InverseFunctionalProperty),
- (oneOf, unionOf, intersectionOf. complementOf)
- (Restriction, onProperty)
- (someValuesFrom, allValuesFrom, hasValue)
- (cardinality, minCardinality, maxCardinality)
- (qualifiedCardinality, minQualifiedCardinality, maxQualifiedCardinality, onClass)
Owlready2
This lab will re-write the same OWL expressions as in an earlier lab, but using owlready2 instead of rdflib.
The Project description and section What can I do with Owlready2? gives a brief introduction to installing and getting started with owlready2. You will find more documentation at Welcome to Owlready2's Documentation
For example:
# A graduate is a student with at least one degree.
with onto:
class Student(Thing): pass
class Degree(Thing): pass
class hasDegree(Student >> Degree): pass
class Graduate(Student):
is_a = [hasDegree.some(Degree)]
Tasks
Re-write the same OWL expressions as in an earlier lab, but using owlready2 instead of rdflib:
- anyone who is a graduate has at least one degree
- anyone who is a university graduate has at least one degree from a university
- a grade is either an A, B, C, D, E or F
- a straight A student is a student that has only A grades
- a graduate has no F grades
- a student has a unique student number
- each student has exactly one average grade
- a course is either a bachelor, a master or a Ph.D course
- a bachelor student takes only bachelor courses
- a master student takes only master courses, except for at most one bachelor course
- a Ph.D student takes only Ph.D courses, except for at most two masters courses
- a Ph.D. student cannot take any bachelor course
Code to get started
(These need more testing!)
Empty an ontology (otherwise owlready2 remembers ontologies between sessions!):
Print an ontology:
Print an ontology without standard triples:
To print an ontology without standard triples, you must first run this code at the beginning of the program:
If You Have More Time
Populate the ontology with individals, such as:
with onto:
cade = Student()
infosci = Degree()
cade.hasDegree.append(infosci)Try to use Hermit as in the lecture to infer additional triples. IMPORANT: Neither Hermit/Pellet nor OWL-RL are able to reason with the full OWL-DL. But unlike OWL-RL, Owlready2 supports reaosning over many types of restrictions.
