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
Guide for a 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 Syntax.
Status of this document
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
Publication as a Candidate Recommendation does not imply
endorsement by the W3C Membership. This is a draft document and may be
updated, replaced or obsoleted by other documents at any time. It is
inappropriate to cite this document as other than "work in
This draft is one of six
parts of the Candidate
Recommendation (CR) for OWL, the Web Ontology Language. It has
been developed by the Web
Ontology Working Group as part of the W3C Semantic Web Activity (Activity Statement, Group Charter) for
publication on 18 August 2003.
The design of OWL expressed in earlier versions of these documents
has been widely reviewed and satisfies the Working Group's technical
requirements. The Working Group has addressed
all comments received, making changes as necessary. Changes to
this document since the Last Call
Working Draft are detailed in the change log.
The Working Group now hopes to gather experience from the growing
number of OWL
implementations in order to increase confidence in the language
and meet specific exit criteria.
This CR period will extend until at least . After
that date, when and if the exit criteria are met, the group intends to
Proposed Recommendation status.
Please send reports of implementation experience to email@example.com
Reports of any success or difficulty with the Test Cases
are encouraged, and reports received by 20 September 2003 will be
particularly helpful. General discussion of related technology is
welcome at firstname.lastname@example.org (archive).
Although OWL is essentially stable, later versions of these
documents are expected to contain minor improvements. The test site is likely to
include new, clarifying tests, even during this CR period.
Additionally, the design of OWL depends in part on the design of RDF,
and at this time the relevant RDF specifications are only Working
Drafts. It is therefore possible that unanticipated changes in RDF
may require changes to OWL.
The W3C maintains a list of any
patent disclosures related to this work.
The three sublanguages of OWL
The structure of this document
OWL Lite Synopsis
OWL DL and OWL Full Synopsis
Language Description of OWL Lite
OWL Lite RDF Schema Features
OWL Lite Equality and Inequality
OWL Lite Property Characteristics
OWL Lite Property Type Restrictions
OWL Lite Restricted Cardinality
OWL Lite Class Intersection
OWL Lite Header Information
OWL Lite Annotation Properties
Incremental 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
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:
The suggested 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
OWL Overview gives a simple introduction to OWL by
providing a language feature listing with very brief
Guide demonstrates the use of the OWL language by
providing an extended example. It also provides a
of the terminology used in these documents;
Reference gives a systematic and compact (but still
informally stated) description of all the modelling
primitives of OWL;
OWL Semantics and Abstract Syntax document is the final
and formally stated normative definition of the language;
Web Ontology Language Test Cases document contains a
large set of test cases for the language;
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.
Use Cases and Requirements Document provides more
on ontologies, motivates the need for a Web Ontology
Language in terms of
use cases, and formulates
objectives for OWL.
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 these documents.
XML Schema is
a language for restricting the structure of XML
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.
RDF Schema is a vocabulary for describing properties
and classes of RDF resources, with a semantics for
generalization-hierarchies of such properties and
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 provides three increasingly expressive sublanguages
designed for use by specific communities of implementers and
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
section on OWL Lite in the OWL Reference for further
supports those users who want the maximum expressiveness
while retaining computational completeness (all
conclusions are guaranteed to be computed) 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
logics, a field of research that has studied the
logics that form the formal foundation of 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
Every valid OWL DL conclusion is a valid OWL Full
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 and OWL
Full. 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
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 emposed
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 simililarly 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
of the OWL Reference.
1.4 The structure of this
This document first describes the features from OWL Lite,
followed by a description from 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
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 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
Reference for definitions). Each language feature is
hyperlinked to the appropriate place in the
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
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 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 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 ObjectProperties), 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 a Datatype
rdfs:subPropertyOf: 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
A domain of a property limits the individuals to which the
property can be applied. If a property relates 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 local
restrictions for more information.
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 indivual 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
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
The following OWL Lite features are related to equality or
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 vice versa.
equivalentProperty: 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.
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
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
3.3 OWL Lite Property
There are special identifiers in OWL Lite that are used to
provide information concerning properties and their values.
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.
TransitiveProperty: 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
OWL 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
Semantics and Abstract Syntax document for more
SymmetricProperty: 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.
FunctionalProperty : 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.
InverseFunctionalProperty: 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 same individual.
3.4 OWL Lite Property Type
OWL Lite allows restrictions to be placed on how
properties can be used by instances of a class. The following
two restrictions limit which values can be used while the next
section's restrictions limit how many values can be used.
allValuesFrom: 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 property.
someValuesFrom: 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
3.5 OWL Lite Restricted
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 publically available webont mail
archives with the most relevant message at
minCardinality: 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).
maxCardinality: 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
3.6 OWL Lite Class Intersection
OWL Lite contains an intersection constructor but limits
intersectionOf: 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
OWL uses the RDF mechanisms for data values.
OWL Guide for a
more detailed description.
3.8 OWL Lite Header Information
OWL Lite supports notions of ontology inclusion and
relationships and attaching information to ontologies.
Reference for details and the
Guide for examples.
3.9 OWL Lite Annotation
OWL Lite allows annotations on classes, properties,
individuals and ontology headers. The use of these annotations
is subject to certain restrictions. See the
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
Reference for further details.
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
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
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
reference document, the
Guide, and the
Semantics and Abstract Syntax document for more details.
Previous versions (
July 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
(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.
(TheNetherlands itself is an instance of the class of
OWL Full allows the statement that classes are disjoint.
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.
complementOf, intersectionOf (Boolean
combinations): OWL DL allows 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 member
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 be restricted to cardinality 0).
complex 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
This document is the result of extensive discussions
within the Web Ontology Working Group as a whole. The members
of this working group were 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, JérômeEuzenat, Dieter
Fensel, Tim Finin, Nicholas Gibbins, Sandro Hawke,
Pat Hayes, Jeff Heflin,
Ziv Hellman, James Hendler, Bernard Horan, Masahiro Hori, Ian
Horrocks, Francesco Iannuzzelli, Mario Jeckle, Ruediger Klein,
Natasha Kravtsova, Ora Lassila, Alexander Maedche, Massimo
Marchiori, Deborah McGuinness, Libby Miller, Enrico Motta, Leo
Obrst, Laurent Olivry , Peter Patel-Schneider, Martin Pike,
Marwan Sabbouh, Guus Schreiber, Noboru Shimizu, Michael Sintek,
Michael Smith, Ned Smith, John Stanton, Lynn Andrea Stein,
Herman ter Horst, Lynne R. Thompson, David Trastour, Frank van
Harmelen, Raphael Volz, Evan Wallace, Christopher Welty,
Charles White, and John Yanosy.
OWL Web Ontology Language Guide. Mike Smith,
Chris Welty, and Deborah L. McGuinness. W3C Candidate
Recommendation 18 August 2003.
Abstract Syntax and Semantics
OWL Web Ontology Language Semantics and Abstract
Syntax, Peter F. Patel-Schneider, Patrick Hayes,
and Ian Horrocks. W3C Candidate Recommendation 18 August
OWL Web Ontology Language Reference. Mike Dean,
Guus Schreiber, Sean Bechhofer, Frank van Harmelen, Jim
Hendler, Ian Horrocks, Deborah L. McGuinness, Peter F.
Patel-Schneider, and Lynn Andrea Stein. W3C Candidate
Recommendation 18 August 2003.
OWL Web Ontology Language Overview.
Deborah L. McGuinness and Frank van Harmelen. W3C Candidate
Recommendation 18 August 2003.
OWL Web Ontology Language Test Cases. Jeremy J.
Carroll and Jos De Roo. W3C Candidate Recommendation 18
Web Ontology Issue Status. Michael K.
Smith, ed. 27 June 2003.
OWL Web Ontology Language Use Cases and
Requirements. Jeff Heflin. W3C Candidate
Recommendation 18 August 2003.
Reference Description . Dan Connolly, Frank van
Harmelen, Ian Horrocks, Deborah L. McGuinness, Peter F.
Patel-Schneider, and Lynn Andrea Stein. W3C Note 18
Language (XML) .
Resource Description Frameswork (RDF): Concepts and
Abstract Syntax. Grahm Klyne and Jeremy Carroll.
W3C Working Draft, November 2002.
Vocabulary Description Language 1.0: RDF Schema.
Dan Brickley and R. V. Guha. W3C Working Draft 23 January
Description Logic Handbook. Franz Baader, Diego
Calvanese, Deborah McGuinness, Daniele Nardi, Peter
Patel-Schneider, editors. Cambridge University Press, 2003;
Description Logics Home
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
incorporated all Lasilla's comment, including replacing
"machine readability" by "machine interpretability" and
Added sentence on lower complexity class of OWL Lite, as
proposed by Jim Hendler
Added first sentence to section 1, after Sandro Hawke's
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/