WSML – a Language for WSMO - Enabling Semantic Web Services: The Web Service Modeling Ontology - page 82

wsmlVariant ”http://www.wsmo.org/wsml/wsml − syntax/wsml − flight”
namespace { ”http://example.org/bookOntology#”,
dc ”http:// purl .org/dc/elements/1.1/” }
ontology ”http://example.org/bookOntology”
nonFunctionalProperties
dc#title hasValue ”Example Book Ontology”
dc#description hasValue ”Example ontology about topics and shopping carts”
endNonFunctionalProperties
concept book
title ofType string
hasAuthor ofType author
concept author subConceptOf person
authorOf inverseOf (hasAuthor) ofType book
concept cart
nonFunctionalProperties
dc#description hasValue ”A shopping cart has exactly one id
and zero or more items, which are topics.”
endNonFunctionalProperties
id ofType (1) string
items ofType book
instance crimeAndPunishment memberOf book
title hasValue ”Crime and Punishment”
hasAuthor hasValue dostoyevsky
relation authorship( impliesType author, impliesType document)
nonFunctionalProperties
dc#relation hasValue authorshipFromAuthor
endNonFunctionalProperties
axiom authorshipFromAuthor
definedBy
authorship(?x,?y) : − ?x[authorOf hasValue ?y] memberOf author.
Listing 7.1. An example WSML ontology
Attribute definitions can take two forms, namely constraining (using
ofType )and inferring (using impliesType ) attribute definitions. 2 Constraining
attribute definitions define a typing constraint on the values of an attribute,
similar to integrity constraints in databases; inferring attribute definitions im-
ply that the type of the values of the attribute is inferred from the attribute
definition, similar to the range restrictions on properties in RDFS [20] and
OWL [32]. Each attribute definition may have a number of features associ-
ated with it, namely, transitivity, symmetry, reflexivity, and the inverse of an
attribute, as well as minimal and maximal cardinality constraints.
Constraining attribute definitions, and also cardinality constraints, require
closed-world reasoning and are thus not allowed in WSML-Core and WSML-
DL. As opposed to the features of roles in description logics, features of at-
tributes such as transitivity, symmetry, reflexivity, and inverse attributes are
local to a concept in WSML. Thus, none of these features may be used in
WSML-Core and WSML-DL. For a description of the motivation for the use
of constraining attributes, see [31].
2 The distinction between inferring and constraining attribute definitions is ex-
plained in more detail in [31, Section 2].