OWL Web Ontology Language
W3C Recommendation 31 December
PRE-PUBLICATION DRAFT. This document is being
prepared for possible publication by the W3C, but it may change, be delayed, or
never be published. The "Version" URIs and "Status of this Document" section may
reflect its planned location and status, not present reality.
- This version:
- Latest version:
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- Deborah L. McGuinness (Knowledge Systems Laboratory, Stanford University)
- Frank van Harmelen (Vrije Universiteit, Amsterdam)
2003 W3C® (MIT, ERCIM,
Keio), All Rights Reserved. W3C liability,
use and software
licensing rules apply.
The OWL Web Ontology Language is designed for use by applications that need
to process the content of information instead of just presenting information to
humans. OWL facilitates greater machine interpretability of Web content than
that supported by XML, RDF, and RDF Schema (RDF-S) by providing additional
vocabulary along with a formal semantics. OWL has three increasingly-expressive
sublanguages: OWL Lite, OWL DL, and OWL Full.
This document is written for readers who want a first impression of the
capabilities of OWL. It provides an introduction to OWL by informally describing
the features of each of the sublanguages of OWL. Some knowledge of RDF
Schema is useful for understanding this document, but not essential. After
this document, interested readers may turn to the OWL Guide for more detailed
descriptions and extensive examples on the features of OWL. The normative formal
definition of OWL can be found in the OWL Semantics and Abstract
Status of this document
three sublanguages of OWL
structure of this document
- OWL Lite
- OWL DL
and OWL Full Synopsis
Description of OWL Lite
- OWL Lite
RDF Schema Features
- OWL Lite
Equality and Inequality
- OWL Lite
- OWL Lite
- OWL Lite
- OWL Lite
- OWL Lite
- OWL Lite
- OWL Lite
Language Description of OWL DL and OWL Full
This document describes the OWL Web Ontology Language. OWL is intended to be
used when the information contained in documents needs to be processed by
applications, as opposed to situations where the content only needs to be
presented to humans. OWL can be used to explicitly represent the meaning of
terms in vocabularies and the relationships between those terms. This
representation of terms and their interrelationships is called an ontology. OWL
has more facilities for expressing meaning and semantics than XML, RDF, and
RDF-S, and thus OWL goes beyond these languages in its ability to represent
machine interpretable content on the Web. OWL is a revision of the DAML+OIL
web ontology language incorporating lessons learned from the design and
application of DAML+OIL.
1.1 Document Roadmap
The OWL Language is described by a set of documents, each fulfilling a
different purpose, and catering to a different audience. The following provides
a brief roadmap for navigating through this set of documents:
reading order of the first four documents is as given since they have been
listed in increasing degree of technical content. The last two documents
complete the documentation set.
- This OWL Overview gives a
simple introduction to OWL by providing a language feature listing with very
brief feature descriptions;
- The OWL Guide demonstrates
the use of the OWL language by providing an extended example. It also provides
a glossary of the
terminology used in these documents;
- The OWL Reference gives a
systematic and compact (but still informally stated) description of all the
modelling primitives of OWL;
- The OWL Semantics and
Abstract Syntax document is the final and formally stated normative
definition of the language;
- The OWL Web Ontology Language
Test Cases document contains a large set of test cases for the language;
- The OWL Use Cases and
Requirements document contains a set of use cases for a web ontology
language and compiles a set of requirements for OWL.
1.2 Why OWL?
The Semantic Web is a vision for the future of the Web in which information
is given explicit meaning, making it easier for machines to automatically
process and integrate information available on the Web. The Semantic Web will
build on XML's ability to define customized tagging schemes and RDF's flexible
approach to representing data. The first level above RDF required for the
Semantic Web is an ontology language what can formally describe the meaning of
terminology used in Web documents. If machines are expected to perform useful
reasoning tasks on these documents, the language must go beyond the basic
semantics of RDF Schema. The OWL Use
Cases and Requirements Document provides more details on ontologies,
motivates the need for a Web Ontology Language in terms of six use cases, and
OWL has been designed to meet this need for a Web Ontology Language. OWL is
part of the growing stack of W3C recommendations related to the Semantic Web.
XML provides a surface syntax for
structured documents, but imposes no semantic constraints on the meaning of
XML Schema is a language for
restricting the structure of XML documents and also extends XML with datatypes.
RDF is a
datamodel for objects ("resources") and relations between them, provides a
simple semantics for this datamodel, and these datamodels can be represented
in an XML syntax.
is a vocabulary for describing properties and classes of RDF resources, with a
semantics for generalization-hierarchies of such properties and classes.
OWL adds more vocabulary for describing properties and classes: among
others, relations between classes (e.g. disjointness), cardinality (e.g.
"exactly one"), equality, richer typing of properties, characteristics of
properties (e.g. symmetry), and enumerated classes.
1.3 The three sublanguages of OWL
OWL provides three increasingly expressive sublanguages designed for use by
specific communities of implementers and users.
OWL Lite supports those
users primarily needing a classification hierarchy and simple constraints. For
example, while it supports cardinality constraints, it only permits
cardinality values of 0 or 1. It should be simpler to provide tool support for
OWL Lite than its more expressive relatives, and OWL Lite provides a quick
migration path for thesauri and other taxonomies. Owl Lite also has a lower
formal complexity than OWL DL, see the section on OWL Lite in the
OWL Reference for further details.
OWL DL supports those users
who want the maximum expressiveness while retaining computational completeness
(all conclusions are guaranteed to be computable) and decidability (all
computations will finish in finite time). OWL DL includes all OWL language
constructs, but they can be used only under certain restrictions (for example,
while a class may be a subclass of many classes, a class cannot be an instance
of another class). OWL
DL is so named due to its correspondence with description
logics, a field of research that has studied the logics that form the
formal foundation of OWL.
OWL Full is meant for
users who want maximum expressiveness and the syntactic freedom of RDF with no
computational guarantees. For example, in OWL Full a class can be treated
simultaneously as a collection of individuals and as an individual in its own
right. OWL Full allows an ontology to augment the meaning of the pre-defined
(RDF or OWL) vocabulary. It is unlikely that any reasoning software will be
able to support complete reasoning for every feature of OWL Full.
Each of these sublanguages is an extension of its simpler predecessor, both
in what can be legally expressed and in what can be validly concluded. The
following set of relations hold. Their inverses do not.
- Every legal OWL Lite ontology is a legal OWL DL ontology.
- Every legal OWL DL ontology is a legal OWL Full ontology.
- Every valid OWL Lite conclusion is a valid OWL DL conclusion.
- Every valid OWL DL conclusion is a valid OWL Full conclusion.
Ontology developers adopting OWL should consider which sublanguage best suits
their needs. The choice between OWL Lite and OWL DL depends on the extent to
which users require the more-expressive constructs provided by OWL DL.
The choice between OWL DL and OWL Full mainly depends on the extent to
which users require the meta-modeling facilities of RDF Schema (e.g. defining
classes of classes, or attaching properties to classes). When using OWL Full as
compared to OWL DL, reasoning support is less predictable since complete OWL
Full implementations do not currently exist. OWL Full can be viewed as an
extension of RDF, while OWL Lite and OWL DL can be viewed as extensions of a
restricted view of RDF. Every OWL (Lite, DL, Full) document is an RDF document,
and every RDF document is an OWL Full document, but only some RDF documents will
be a legal OWL Lite or OWL DL document. Because of this, some care has to be
taken when a user wants to migrate an RDF document to OWL. When the
expressiveness of OWL DL or OWL Lite is deemed appropriate, some precautions
have to be taken to ensure that the original RDF document complies with the
additional constraints imposed by OWL DL and OWL Lite. Among others, every URI
that is used as a class name must be explicitly asserted to be of type owl:Class
(and similarly for properties), every individual must be asserted to belong to
at least one class (even if only owl:Thing), the URI's used for classes,
properties and individuals must be mutually disjoint. The details of these and
other constraints on OWL DL and OWL Lite are explained in appendix E of the OWL
1.4 The structure of this document
This document first describes the features in OWL Lite, followed by a
description of the features that are added in OWL DL and OWL Full (OWL DL and
OWL Full contain the same features, but OWL Full is more liberal about how these
features can be combined).
2. Language Synopsis This section provides a quick
index to all the language features for OWL Lite, OWL DL, and OWL Full.
In this document, italicized terms are terms in OWL. Prefixes of rdf: or
rdfs: are used when terms are already present in RDF or RDF Schema. Otherwise
terms are introduced by OWL. Thus, the term rdfs:subPropertyOf indicates
that subPropertyOf is already in the rdfs vocabulary (technically : the rdfs
namespace). Also, the term Class is more precisely stated as
owl:Class and is a term introduced by OWL.
2.1 OWL Lite Synopsis
The list of OWL Lite language constructs is given below.
2.2 OWL DL and Full Synopsis
The list of OWL DL and OWL Full language constructs that are in addition to or expand those
of OWL Lite is given below.
3. Language Description of OWL Lite
This section provides an informal description of the OWL Lite language
features. We do not discuss the specific syntax of these features (see the OWL Reference for definitions). Each
language feature is hyperlinked to the appropriate place in the OWL Guide for more examples and
guidance on usage.
OWL Lite uses only some of the OWL language features and has more limitations
on the use of the features than OWL DL or OWL Full. For example, in OWL Lite
classes can only be defined in terms of named superclasses (superclasses cannot
be arbitrary expressions), and only certain kinds of class restrictions can be
used. Equivalence between classes and subclass relationships between classes are
also only allowed between named classes, and not between arbitrary class
expressions. Similarly, restrictions in OWL Lite use only named classes. OWL
Lite also has a limited notion of cardinality - the only cardinalities allowed
to be explicitly stated are 0 or 1.
3.1 OWL Lite RDF Schema Features
The following OWL Lite features related to RDF Schema are included.
- Class: A class
defines a group of individuals that belong together because they share some
properties. For example, Deborah and Frank are both members of the class
Person. Classes can be organized in a specialization hierarchy using subClassOf.
There is a built-in most general class named Thing that is the class of all
individuals and is a superclass of all OWL classes. There is also a built-in most
specific class named Nothing that is the class that has no instances and a
subclass of all OWL classes.
Class hierarchies may be created by making one or more statements that a class
is a subclass of another class. For example, the class Person could be stated
to be a subclass of the class Mammal. From this a reasoner can deduce that if
an individual is a Person, then it is also a Mammal.
Properties can be used to state relationships between individuals or from
individuals to data values. Examples of properties include hasChild,
hasRelative, hasSibling, and hasAge. The first three can be used to relate an
instance of a class Person to another instance of the class Person (and are
thus occurences of
ObjectProperty), and the last (hasAge) can be used to relate an
instance of the class Person to an instance of the datatype Integer (and is
thus an occurence of DatatypeProperty). Both owl:ObjectProperty and owl:DatatypeProperty are subclasses of the RDF class rdf:Property.
Property hierarchies may be created by making one or more statements that a
property is a subproperty of one or more other properties. For example,
hasSibling may be stated to be a subproperty of hasRelative. From this a
reasoner can deduce that if an individual is related to another by the
hasSibling property, then it is also related to the other by the hasRelative
- rdfs:domain: A
domain of a property limits the individuals to which the property can be
applied. If a property relates an individual to another individual, and the
property has a class as one of its domains, then the individual must belong to
the class. For example, the property hasChild may be stated to have the domain
of Mammal. From this a reasoner can deduce that if Frank hasChild Anna, then
Frank must be a Mammal. Note that rdfs:domain is called a global
restriction since the restriction is stated on the property and not just on
the property when it is associated with a particular class. See the discussion
below on property restrictions for more information.
- rdfs:range: The
range of a property limits the individuals that the property may have as its
value. If a property relates an individual to another individual, and the
property has a class as its range, then the other individual must belong to
the range class. For example, the property hasChild may be stated to have the
range of Mammal. From this a reasoner can deduce that if Louise is related to
Deborah by the hasChild property, (i.e., Deborah is the child of Louise), then
Deborah is a Mammal. Range is also a global restriction as is domain above.
Again, see the discussion below on local restrictions (e.g. AllValuesFrom)
for more information.
- Individual : Individuals are instances of
classes, and properties may be used to relate one individual to another. For
example, an individual named Deborah may be described as an instance of the
class Person and the property hasEmployer may be used to relate the individual
Deborah to the individual StanfordUniversity.
3.2 OWL Lite Equality and Inequality The
following OWL Lite features are related to equality or inequality.
- equivalentClass : Two classes may be
stated to be equivalent. Equivalent classes have the same instances. Equality
can be used to create synonymous classes. For example, Car can be stated to be
equivalentClass to Automobile. From this a reasoner can deduce that any
individual that is an instance of Car is also an instance of Automobile and
Two properties may be stated to be equivalent. Equivalent properties relate
one individual to the same set of other individuals. Equality may be used to
create synonymous properties. For example, hasLeader may be stated to be the
equivalentProperty to hasHead. From this a reasoner can deduce that if
X is related to Y by the property hasLeader, X is also related to Y by the
property hasHead and vice versa. A reasoner can also deduce that hasLeader is
a subproperty of hasHead and hasHead is a subProperty of hasLeader.
- sameAs: Two
individuals may be stated to be the same. These constructs may be used to
create a number of different names that refer to the same individual. For
example, the individual Deborah may be stated to be the same individual as
An individual may be stated to be different from other individuals. For
example, the individual Frank may be stated to be different from the
individuals Deborah and Jim. Thus, if the individuals Frank and Deborah are
both values for a property that is stated to be functional (thus the property
has at most one value), then there is a contradiction. Explicitly stating that
individuals are different can be important in when using languages such as OWL
(and RDF) that do not assume that individuals have one and only one name. For
example, with no additional information, a reasoner will not deduce that Frank
and Deborah refer to distinct individuals.
A number of individuals may be stated to be mutually distinct in one
allDifferent statement. For example, Frank, Deborah, and Jim could be stated
to be mutually distinct using the allDifferent construct. Unlike the
differentFrom statement above, this would also enforce that Jim and Deborah
are distinct (not just that Frank is distinct from Deborah and Frank is
distinct from Jim). The allDifferent construct is particularly useful when
there are sets of distinct objects and when modelers are interested in
enforcing the unique names assumption within those sets of objects. It is
used in conjunction
with distinctMembers to state that
all members of a list are distinct and pairwise disjoint.
3.3 OWL Lite Property Characteristics There
are special identifiers in OWL Lite that are used to provide information
concerning properties and their values. The distinction between
ObjectProperty and DatatypeProperty is
mentioned above in the property description.
One property may be stated to be the inverse of another property. If the
property P1 is stated to be the inverse of the property P2, then if X is
related to Y by the P2 property, then Y is related to X by the P1 property.
For example, if hasChild is the inverse of hasParent and Deborah hasParent
Louise, then a reasoner can deduce that Louise hasChild Deborah.
Properties may be stated to be transitive. If a property is transitive, then
if the pair (x,y) is an instance of the transitive property P, and the pair
(y,z) is an instance of P, then the pair (x,z) is also an instance of P. For
example, if ancestor is stated to be transitive, and if Sara is an ancestor of
Louise (i.e., (Sara,Louise) is an instance of the property ancestor) and
Louise is an ancestor of Deborah (i.e., (Louise,Deborah) is an instance of the
property ancestor), then a reasoner can deduce that Sara is an ancestor of
Deborah (i.e., (Sara,Deborah) is an instance of the property ancestor).
Lite (and OWL DL) impose the side condition that transitive properties (and
their superproperties) cannot have a maxCardinality 1 restriction. Without
this side-condition, OWL Lite and OWL DL would become undecidable languages.
See the property axiom section of the OWL Semantics and Abstract
Syntax document for more information.
Properties may be stated to be symmetric. If a property is symmetric, then if
the pair (x,y) is an instance of the symmetric property P, then the pair (y,x)
is also an instance of P. For example, friend may be stated to be a symmetric
property. Then a reasoner that is given that Frank is a friend of Deborah can
deduce that Deborah is a friend of Frank.
: Properties may be stated to have a unique value. If a property is a
FunctionalProperty, then it has no more than one value for each individual (it
may have no values for an individual). This characteristic has been referred
to as having a unique property. FunctionalProperty is shorthand for stating
that the property's minimum cardinality is zero and its maximum cardinality is
1. For example, hasPrimaryEmployer may be stated to be a FunctionalProperty.
From this a reasoner may deduce that no individual may have more than one
primary employer. This does not imply that every Person must have at least one
primary employer however.
Properties may be stated to be inverse functional. If a property is inverse
functional then the inverse of the property is functional. Thus the inverse of
the property has at most one value for each individual. This characteristic
has also been referred to as an unambiguous property. For example,
hasUSSocialSecurityNumber (a unique identifier for United States residents)
may be stated to be inverse functional (or unambiguous). The inverse of this
property (which may be referred to as isTheSocialSecurityNumberFor) has at
most one value for any individual in the class of social security numbers.
Thus any one person's social security number is the only value for their
isTheSocialSecurityNumberFor property. From this a reasoner can deduce that no
two different individual instances of Person have the identical US Social
Security Number. Also, a reasoner can deduce that if two instances of Person
have the same social security number, then those two instances refer to the
3.4 OWL Lite Property Restrictions OWL
Lite allows restrictions to be placed on how properties can be used by instances
of a class. These type (and the cardinality restrictions in the next subsection)
are used within the context of an owl:Restriction.
The owl:onProperty element indicates
the restricted property.
The following two restrictions limit which values can be used while
the next section's restrictions limit how many values can be used.
The restriction allValuesFrom is stated on a property with respect to a class.
It means that this property on this particular class has a local range
restriction associated with it. Thus if an instance of the class is related by
the property to a second individual, then the second individual can be
inferred to be an instance of the local range restriction class. For example,
the class Person may have a property called hasDaughter restricted to have
allValuesFrom the class Woman. This means that if an individual person Louise
is related by the property hasDaughter to the individual Deborah, then from
this a reasoner can deduce that Deborah is an instance of the class Woman.
This restriction allows the property hasDaughter to be used with other
classes, such as the class Cat, and have an appropriate value restriction
associated with the use of the property on that class. In this case,
hasDaughter would have the local range restriction of Cat when associated with
the class Cat and would have the local range restriction Person when
associated with the class Person. Note that a reasoner can not deduce from an
allValuesFrom restriction alone that there actually is at least one value for
The restriction someValuesFrom is stated on a property with respect to
a class. A particular class may have a restriction on a property that at least
one value for that property is of a certain type. For example, the class
SemanticWebPaper may have a someValuesFrom restriction on the
hasKeyword property that states that some value for the hasKeyword
property should be an instance of the class SemanticWebTopic. This allows for
the option of having multiple keywords and as long as one or more is an
instance of the class SemanticWebTopic, then the paper would be consistent
with the someValuesFrom restriction. Unlike allValuesFrom,
someValuesFrom does not restrict all the values of the property to be
instances of the same class. If myPaper is an instance of the SemanticWebPaper
class, then myPaper is related by the hasKeyword property to at least
one instance of the SemanticWebTopic class. Note that a reasoner can not
deduce (as it could with allValuesFrom restrictions) that all
values of hasKeyword are instances of the SemanticWebTopic class
3.5 OWL Lite Restricted Cardinality
OWL Lite includes a limited form of cardinality restrictions. OWL (and OWL
Lite) cardinality restrictions are referred to as local restrictions, since they
are stated on properties with respect to a particular class. That is, the
restrictions constrain the cardinality of that property on instances of that
class. OWL Lite cardinality restrictions are limited because they only allow
statements concerning cardinalities of value 0 or 1 (they do not allow arbitrary
values for cardinality, as is the case in OWL DL and OWL Full).
Alternate namings for these restricted forms of cardinality were
discussed. Current recommendations are to include any such names in a front end
system. More on this topic is available on the publicly available webont mail
archives with the most relevant message at http://lists.w3.org/Archives/Public/www-webont-wg/2002Oct/0063.html.
Cardinality is stated on a property with respect to a particular class. If a
minCardinality of 1 is stated on a property with respect to a class,
then any instance of that class will be related to at least one individual by
that property. This restriction is another way of saying that the property is
required to have a value for all instances of the class. For example,
the class Person would not have any minimum cardinality restrictions stated on
a hasOffspring property since not all persons have offspring. The class
Parent, however would have a minimum cardinality of 1 on the hasOffspring
property. If a reasoner knows that Louise is a Person, then nothing can be
deduced about a minimum cardinality for her hasOffspring property. Once it is
discovered that Louise is an instance of Parent, then a reasoner can deduce
that Louise is related to at least one individual by the hasOffspring
property. From this information alone, a reasoner can not deduce any maximum
number of offspring for individual instances of the class parent. In OWL Lite
the only minimum cardinalities allowed are 0 or 1. A minimum cardinality of
zero on a property just states (in the absence of any more specific
information) that the property is optional with respect to a class. For
example, the property hasOffspring may have a minimum cardinality of zero on
the class Person (while it is stated to have the more specific information of
minimum cardinality of one on the class Parent).
Cardinality is stated on a property with respect to a particular class. If a
maxCardinality of 1 is stated on a property with respect to a class,
then any instance of that class will be related to at most one individual by
that property. A maxCardinality 1 restriction is sometimes called a functional
or unique property. For example, the property hasRegisteredVotingState on the
class UnitedStatesCitizens may have a maximum cardinality of one (because
people are only allowed to vote in only one state). From this a reasoner can
deduce that individual instances of the class USCitizens may not be related to
two or more distinct individuals through the hasRegisteredVotingState
property. From a maximum cardinality one restriction alone, a reasoner can not
deduce a minimum cardinality of 1. It may be useful to state that certain
classes have no values for a particular property. For example, instances of
the class UnmarriedPerson should not be related to any individuals by
the property hasSpouse. This situation is represented by a maximum cardinality
of zero on the hasSpouse property on the class UnmarriedPerson.
Cardinality is provided as a convenience when it is useful to state that a
property on a class has both minCardinality 0 and maxCardinality
0 or both minCardinality 1 and maxCardinality 1. For example,
the class Person has exactly one value for the property hasBirthMother. From
this a reasoner can deduce that no two distinct individual instances of the
class Mother may be values for the hasBirthMother property of the same person.
3.6 OWL Lite Class Intersection OWL Lite
contains an intersection constructor but limits its usage.
OWL Lite allows intersections of named classes and restrictions. For example,
the class EmployedPerson can be described as the intersectionOf Person
and EmployedThings (which could be defined as things that have a minimum
cardinality of 1 on the hasEmployer property). From this a reasoner may deduce
that any particular EmployedPerson has at least one employer.
3.7 OWL Datatypes
OWL uses the RDF mechanisms for data values. See
the OWL Guide section on datatypes for a more detailed
description of the built-in OWL datatypes taken largely from the XML Schema datatypes.
3.8 OWL Lite Header Information OWL Lite
supports notions of ontology inclusion and relationships and attaching
information to ontologies. See
the OWL Reference for details and
the OWL Guide for examples.
3.9 OWL Lite Annotation Properties OWL Lite
allows annotations on classes, properties, individuals and ontology headers. The
use of these annotations is subject to certain restrictions. See the section on Annotations in the
OWL Reference for details.
3.10 OWL Lite Versioning RDF already has a
small vocabulary for describing versioning information. OWL significantly
extends this vocabulary. See the OWL Reference for further
4. Incremental Language Description of OWL DL and OWL
Full Both OWL DL and OWL Full use the same vocabulary although OWL DL is
subject to some restrictions. Roughly, OWL DL requires type separation (a class
can not also be an individual or property, a property can not also be an
individual or class). This implies that restrictions cannot be applied to the
language elements of OWL itself (something that is allowed in OWL Full).
Furthermore, OWL DL requires that properties are either ObjectProperties or
DatatypeProperties: DatatypeProperties are relations between instances of
classes and RDF literals and XML Schema datatypes, while ObjectProperties are
relations between instances of two classes. The OWL Semantics and Abstract Syntax
document explains the distinctions and limitations. We describe the OWL DL and
OWL Full vocabulary that extends the constructions of OWL Lite below.
This document provides an overview of
the Web Ontology Language by providing a brief introduction to why one might
need a Web ontology language and how OWL fits in with related W3C languages. It
also provides a brief description of the three OWL sublanguages: OWL Lite, OWL
DL, and OWL Full along with a feature synopsis for each of the languages. This
document is an update to the Feature Synopsis Document. It provides simple
descriptions of the constructs along with simple examples. It references the OWL reference document, the OWL Guide, and the OWL Semantics and Abstract Syntax
document for more details. Previous versions (
December 15, 2003,
5, 2003, August 18, 2003,
30, 2003, May
1, 2003, March
20, 2003, January
2, 2003, July
29, 2002, July
8, 2002, June
23, 2002, May
26, 2002, and May
15, 2002) of this document provide the historical view of the evolution of
OWL Lite and the issues discussed in its evolution.
(enumerated classes): Classes can be described by enumeration of the
individuals that make up the class. The members of the class are exactly the
set of enumerated individuals; no more, no less. For example, the class of
daysOfTheWeek can be described by simply enumerating the individuals Sunday,
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday. From this a reasoner
can deduce the maximum cardinality (7) of any property that has daysOfTheWeek
as its allValuesFrom restriction.
(property values): A property can be required to have a certain individual as
a value (also sometimes referred to as property values). For example,
instances of the class of dutchCitizens can be characterized as those people
that have theNetherlands as a value of their nationality. (The nationality
value, theNetherlands, is an instance of the class of Nationalities).
Classes may be stated to be disjoint from each other. For example, Man and
Woman can be stated to be disjoint classes. From this disjointWith statement,
a reasoner can deduce an inconsistency when an individual is stated to be an
instance of both and similarly a reasoner can deduce that if A is an instance
of Man, then A is not an instance of Woman.
- unionOf, complementOf,
intersectionOf (Boolean combinations): OWL DL and OWL Full allow arbitrary
Boolean combinations of classes and restrictions: unionOf, complementOf, and
intersectionOf. For example, using unionOf, we can state that a class contains
things that are either USCitizens or DutchCitizens. Using complementOf, we
could state that children are not SeniorCitizens. (i.e. the class
Children is a subclass of the complement of SeniorCitizens). Citizenship of
the European Union could be described as the union of the citizenship of all
maxCardinality, cardinality (full cardinality): While in OWL Lite,
cardinalities are restricted to at least, at most or exactly 1 or 0, full OWL
allows cardinality statements for arbitrary non-negative integers. For example
the class of DINKs ("Dual Income, No Kids") would restrict the cardinality of
the property hasIncome to a minimum cardinality of two (while the property
hasChild would have to be restricted to cardinality 0).
classes : In many constructs, OWL Lite restricts the syntax to
single class names (e.g. in subClassOf or equivalentClass statements). OWL
Full extends this restriction to allow arbitrarily complex class descriptions,
consisting of enumerated classes, property restrictions, and Boolean
combinations. Also, OWL Full allows classes to be used as instances (and OWL
DL and OWL Lite do not). For more on this topic, see the "Design for Use"
section of the Guide document.
- [OWL Overview]
- OWL Web Ontology Language Overview, Deborah L. McGuinness and Frank van Harmelen, Editors, W3C Recommendation, 31 December 2099, http://www.w3.org/2001/sw/WebOnt/TR/STAGE-owl-features/ . Latest version available at http://www.w3.org/TR/owl-features/ .
- [OWL Guide]
- OWL Web Ontology Language Guide, Michael K. Smith, Chris Welty, and Deborah L. McGuinness, Editors, W3C Recommendation, 31 December 2099, http://www.w3.org/2001/sw/WebOnt/TR/STAGE-owl-guide/ . Latest version available at http://www.w3.org/TR/owl-guide/ .
- [OWL Reference]
- OWL Web Ontology Language Reference, Mike Dean and Guus Schreiber, Editors, W3C Recommendation, 31 December 2099, http://www.w3.org/2001/sw/WebOnt/TR/STAGE-owl-ref/ . Latest version available at http://www.w3.org/TR/owl-ref/ .
- [OWL Abstract Syntax and Semantics]
- OWL Web Ontology Language Semantics and Abstract Syntax, Peter F. Patel-Schneider, Pat Hayes, and Ian Horrocks, Editors, W3C Recommendation, 31 December 2099, http://www.w3.org/2001/sw/WebOnt/TR/STAGE-owl-semantics/ . Latest version available at http://www.w3.org/TR/owl-semantics/ .
- [OWL Test]
- OWL Web Ontology Language Test Cases, Jeremy J. Carroll and Jos De Roo, Editors, W3C Recommendation, 31 December 2099, http://www.w3.org/2001/sw/WebOnt/TR/STAGE-owl-test/ . Latest version available at http://www.w3.org/TR/owl-test/ .
- [OWL Requirements]
- OWL Web Ontology Language Use Cases and Requirements, Jeff Heflin, Editor, W3C Recommendation, 31 December 2099, http://www.w3.org/2001/sw/WebOnt/TR/STAGE-webont-req/ . Latest version available at http://www.w3.org/TR/webont-req/ .
- [OWL Issues]
Ontology Issue Status. Michael K. Smith, ed. 1 November 2003.
- [DAML+OIL Reference]
- DAML+OIL Reference
Description . Dan Connolly, Frank van Harmelen, Ian Horrocks,
Deborah L. McGuinness, Peter F. Patel-Schneider, and Lynn Andrea Stein. W3C
Note 18 December 2001.
- Extensible Markup Language
- [XML Schema]
- XML Schema .
- [RDF/XML Syntax]
Syntax Specification (Revised). Dave Beckett, ed. W3C
Recommendation 31 December 2099. Latest version is
- XML Schema Part 2:
Datatypes - W3C Recommendation, World Wide Web Consortium, 2 May
- [RDF Concepts]
Description Framework (RDF): Concepts and Abstract Syntax. Graham
Klyne and Jeremy J. Carroll, eds. W3C Recommendation 31 December 2099. Latest version is available at
- [RDF Schema]
Vocabulary Description Language 1.0: RDF Schema. Dan Brickley and
R.V. Guha, eds. W3C Recommendation 31 December 2099. Latest version is available at
- [RDF Semantics]
Semantics. Patrick Hayes, ed. W3C Recommendation 31 December 2099.
Latest version is available at
- [Description Logics]
- The Description
Logic Handbook. Franz Baader, Diego Calvanese, Deborah McGuinness,
Daniele Nardi, Peter Patel-Schneider, editors. Cambridge University Press,
Description Logics Home Page.
This document is the result of extensive discussions within the Web Ontology Working Group as a
whole. The participants in this Working Group included: Yasser alSafadi,
Jean-François Baget, James Barnette, Sean Bechhofer, Jonathan Borden, Frederik
Brysse, Stephen Buswell, Jeremy Carroll, Dan Connolly, Peter Crowther, Jonathan
Dale, Jos De Roo, David De Roure, Mike Dean, Larry Eshelman, Jérôme Euzenat, Tim
Finin, Nicholas Gibbins, Sandro Hawke, Patrick Hayes, Jeff Heflin, Ziv Hellman,
James Hendler, Bernard Horan, Masahiro Hori, Ian Horrocks, Jane Hunter,
Francesco Iannuzzelli, Rüdiger Klein, Natasha Kravtsova, Ora Lassila, Massimo
Marchiori, Deborah McGuinness, Enrico Motta, Leo Obrst, Mehrdad Omidvari, Martin
Pike, Marwan Sabbouh, Guus Schreiber, Noboru Shimizu, Michael Sintek, Michael K.
Smith, John Stanton, Lynn Andrea Stein, Herman ter Horst, David Trastour, Frank
van Harmelen, Bernard Vatant, Raphael Volz, Evan Wallace, Christopher Welty,
Charles White, and John Yanosy.
- Added owl:Nothing to OWL Lite.
- Added pointer to last call document under title
- Changed all links to owl-absyn to owl-semantics
- Incorporated Lee Lacy's grammatical comments from public-webont-comments
dated April 21, 2003.
- Incorporated Lee Lacy's other comments: annotation properties, version
properties, and other missing tags in 2.2 (which got reorganised as a result)
- changed hasOffSpring example to hasDaughter (request of Morten
- incorporated all Lasilla's comment, including replacing "machine
readability" by "machine interpretability" and various typo's.
- Added sentence on lower complexity class of OWL Lite, as proposed by Jim
- Added first sentence to section 1, after Sandro Hawke's comment
- Restored link to style file
- Added link to test document and May 1 version
- Added references section
- Changed back to relative references to sections
- Changed links to http://www.w3.org/TR/xx from previous versions with
updates later to ...TR/2003/CR-xx-20030818/
- Added Change Log since candidate recommendation.
- Deleted Control Ms at the end of all lines.
- Incorporated Jeff Rafter's public
- Updated Status, Document links, date of publication, etc. according to PR
- Two broken links fixed - W3C icon was referenced by referring to local W3c expansion src="OWL Web Ontology Language Overview_files/ as was gif for author. Added full expansion to W3C icon (http://www.w3.org/Icons/w3c_home) and email gif (http://www.w3.org/2001/sw/WebOnt/guide-src/Email.Deborah.McGuinness.gif).
- Removed control Ms at the end of every line introduced with new version transfer.
- Added links to previous version in December 2003.
- Updated document taking Lee Lacy's comments dated January 12, 2004. (Comments mostly small editorial changes, cell spacing change of 30 to 27 in table, ...)
- Included Benjamin Nowack's editorial comments.
- Updated Reference format.