A Catalogue of OWL Ontology AntiPatterns
Catherine Roussey
UniversitØ de Lyon CNRS
UniversitØ Lyon 1, LIRIS
UMR5205
Villeurbanne, France
catherine.roussey@liris.cnrs.fr
Oscar Corcho
Ontology Engineering Group.
Departamento de Inteligencia
Artificial. Universidad PolitØcnica
de Madrid Spain
ocorcho@fi.upm.es
Luis Manuel Vilches
BlÆzquez
Ontology Engineering Group.
Departamento de Inteligencia
Artificial. Universidad PolitØcnica
de Madrid, Spain
lmvilches@ fi.upm.es

ABSTRACT
Debugging inconsistent OWL ontologies is a time-
consuming task. Debugging services included in existing
ontology engineering tools are still far from providing ade-
quate support to ontology developers and domain experts
for this task, due to their lack of efficiency or precision
when explaining the main causes for inconsistencies. We
present a catalogue of common antipatterns found in incon-
sistent ontologies that can be used in combination with
these tools to make this task more effective.
Categories and Subject Descriptors
I.2.4 Knowledge Representation Formalisms and Methods
representation languages
General Terms
Design, Languages, Verification
Keywords
OWL, ontology, debugging, antipattern
1. INTRODUCTION
Several tools exist for debugging OWL ontologies ([4,5]).
These tools aim at isolating inconsistency-leading axioms,
finding the roots of inconsistency problems, which are then
propagated throughout the concept hierarchy. Although
useful, they are still far from optimal in providing adequate
explanations about the reasons for inconsistencies and in
proposing alternatives to resolve them. Besides, in complex
cases the generation of inconsistency explanations takes
several hours, what makes these tools hard to use. As a re-
sult, we found out that domain experts usually change axi-
oms from the original ontology in a somehow random man-
ner, even changing the intended meaning of the real defini-
tions instead of correcting errors in their formalisations.
We made an effort to understand common inconsistency-
leading patterns used by domain experts when implement-
ing OWL ontologies, based on existing ontology design
patterns and knowledge patterns and anti-patterns.
2. PATTERNS AND ANTI-PATTERNS
In contrast to ontology design patterns, the work on anti-
patterns is less detailed ([7, 12]). Four LAPs are presented
in [7], all of them focused on property domains and ranges.
And [12] describes common difficulties for newcomers to
description logics in understanding the logical meaning of
expressions. However, none of them groups anti-patterns in
a common classification.
2.1 A Classification of Ontology Design Anti-
Patterns
We have identified a set of patterns that are commonly used
by domain experts in their DL formalisations and OWL
implementations, and that normally result in inconsisten-
cies. We have categorized them into three groups:
• Logical Anti-Patterns (LAP). They represent errors that
DL reasoners detect.
• Non-Logical (aka Cognitive) Anti-patterns (NLAP).
They represent possible modelling errors that are not
detected by reasoners (they are not logical but model-
ling errors, which may be due to a misunderstanding of
the logical consequences of the used expression).
• Guidelines (G). They represent complex expressions
used in definitions that are logically correct, but in
which the ontology developer could have used other
simpler alternatives for encoding the same knowledge.
2.2 Logical Antipatterns
AntiPattern AndIsOr (AIO)
C1⊆ ∃R.(C2∩C3), disj(C2,C3)1
This is a common modelling error that appears due to the
fact that in common linguistic usage, and and or do not
correspond consistently to logical conjunction and disjunc-
tion respectively [12].
AntiPattern OnlynessIsLoneliness (OIL)
C1⊆∀R.C2, C1⊆∀R.C3, disj(C2,C3)
The ontology developer has created a universal restriction
to say that C1 can only be linked with R role to C2. Next, a
new universal restriction is added saying that C1 can only
be linked with R to C3, disjoint with C2. In general, this
means that the ontologist forgot the previous axiom.

1
This does not mean that the ontology developer has explicitly
expressed that C2 and C3 are disjoint, but that these two con-
cepts are determined as disjoint from each other by a reasoner.
We use this notation as a shorthand for C2∩C3⊆⊥.

AntiPattern UniversalExistence (UE)
C1⊆∀R.C2, C1⊆∃R.C3, disj(C2,C3)
The ontology developer has added an existential restriction
for a concept without remembering the existence of an in-
consistency-leading universal restriction for that concept.
AntiPattern EquivalenceIsDifference (EID)
C1 ≡ C2, disj(C1,C2)
This inconsistency comes from the fact that the ontology
developer wants to say that C1 is a subclass of C2 (that is,
that C1 is a C2, but at the same time it is different from C2
since he has more information). This anti-pattern is only
common for ontology developers with no previous training
in OWL modelling, since after a short training session they
would discover that they really want to express C1⊆C2.
2.3 Non Logical Anti-Patterns
AntiPattern SynonymeOfEquivalence (SOE)
C1 ≡ C2
The ontology developer wants to express that two classes
C1 and C2 are identical. This is not very useful in a single
ontology that does not import others. Indeed, what the on-
tology developer generally wants to represent is a termino-
logical synonymy relation: the class C1 has two labels: C1
and C2. Usually one of the classes is not used anywhere
else in the axioms defined in the ontology.
AntiPattern SumOfSome (SOS)
C1⊆∃R.C2, C1⊆∃R.C3, disj(C2,C3)
The ontologist has added a new existential restriction with-
out remembering that he has already defined another exis-
tential restriction for the same concept and role. Although
this could be ok in some cases (e.g., a child has at least one
mother and at least one father), in many cases it represents a
modelling error.
AntiPattern SomeMeansAtLeastOne (SMALO)
C1⊆∃R.C2, C1⊆(≥1 R.T)
The cardinality restriction is superfluous.
2.4 Guidelines
Guideline DisjointnessOfComplement (DOC)
C1 ≡ not C2
The ontology developer wants to say that C1 and C2 cannot
share instances. Even if the axiom is correct from a logical
point of view, it is more appropriate to state that C1 and C2
are disjoint.
Guideline Domain&CardinalityConstraints
(DCC)
C1⊆∃R.C2, C1⊆(=2R.T)
Ontology developers with little background in formal logic
find difficult to understand that only does not i mply
some [12]. This antipattern is a counterpart of t hat fact.
Developers may forget that existential restrictions contain a
cardinality constraint: C1⊆∃R.C2 ╞ C1⊆(≥1R.C2). Thus,
when they combine existential and cardinality restrictions,
they may be actually thinking about universal restrictions
with those cardinality constraints.
Guideline GroupAxioms (GA)
C1⊆∀R.C2, C1⊆(≥2R.T) (just as an example)
In order to facilitate the comprehension of complex class
definitions, we recommend grouping all the restrictions of a
class that use the same role R in a single restriction.
Guideline MinIsZero (MIZ)
C1⊆(≥0R.T)
The ontology developer wants to say that C1 can be the
domain of the R role. This restriction has no impact on the
logical model being defined and can be removed.
CONCLUSIONS
In this paper, we collect a list of common anti-patterns that
can be found in ontologies and that cause a large percentage
of inconsistency problems. Besides, we list some anti-
patterns that do not have an impact on the logical conse-
quences of the ontology being developed, but are important
to reduce the number of errors in the intended meaning of
ontologies or to improve their understandability.
ACKNOWLEDGMENTS
This work was partially funded by the Spanish project
GeoBuddies and by the COST Action C21, sponsored by
the EC under the grant number STSM-C21-04241.
REFERENCES
[4]. Horridge M, Parsia B, Sattler U. Laconic and Precise
Justifications in OWL . In Proceedings of the 7th In-
ternational Semantic Web Conference (ISWC),
Karlsruhe, Germany; LNCS 5318: 323-338. (2008).
[5]. Kalyanpur A, Parsia B, Sirin E, Cuenca-Grau B. Re-
pairing Unsatisfiable Classes in OWL Ontologies . I n
Proceedings of the 3rd European Semantic Web Con-
ference (ESWC), Budva, Montenegro; LNCS 4011:
170-184 (2006)
[7] Collection of antipatterns available at http://wiki.loa-
cnr.it/index.php/LoaWiki:MixedDomains
[12] Rector AL, Drummond N, Horridge M, Rogers L,
Knublauch H, Stevens R, Wang H, Wroe C. OWL
Pizzas: Practical Experience of Teaching OWL-DL:
Common Errors & Common Patterns . In Proceedings
of the 14th International Conference Knowledge Ac-
quisition, Modeling and Management (EKAW), Whit-
tlebury Hall, UK. LNCS 3257: 63-81 (2004)