=Paper=
{{Paper
|id=None
|storemode=property
|title=Context Slices: Representing Contexts in OWL
|pdfUrl=https://ceur-ws.org/Vol-671/pat01.pdf
|volume=Vol-671
|dblpUrl=https://dblp.org/rec/conf/semweb/Welty10a
}}
==Context Slices: Representing Contexts in OWL==
https://ceur-ws.org/Vol-671/pat01.pdf
Context Slices: Representing Contexts in OWL
http://ontologydesignpatterns.org/wiki/Submissions:Context_Slices
Chris Welty
IBM Watson Research
Hawthorne, NY 12540, USA
cawelty@gmail.com
ABSTRACT This allows us to represent ceoOf as a binary relation, which
This ontology pattern can be used to represent and reason about seems more natural, and it allows us to use the expressivity of
contextualized statements using standard OWL dialects. The OWL in more ways. We can say of the ceoOf relation that it has
simple idea is to bundle the notion of context into certain nodes in an inverse, hasCeo. We can express cardinality, e.g., a company
the graph, rather than the more typical treatment of contexts as a may have only one CEO within a context. We can say that a
property of the statements themselves. relation is transitive or symmetric. We can express relation
taxonomies in the usual way.
Keywords While clearly OWL does not support RDF reification, and so none
Semantic Web, OWL, RDF, Contexts. of this is possible if statement reification is used. As mentioned
above a more standard way of representing this kind of
information (including time, belief, knowledge, etc.) is to create
1. INTRODUCTION an OWL class that represents the relation holding, with properties
Most information on the web is contextualized somehow, for for the arguments. This approach makes it possible to express
example information may be believed by a person or organization, global but not local range and domain constraints, global but not
it may hold only for some time period, it may have been local cardinality, and symmetry.
reported/observed by an individual, etc. There are myriad Note that the ContextualProjection class should be considered
proposals and logics for context, but none are standards and few disjoint with any of the classes in an ontology that have
have even prototype implementations. projections.
In RDF and other binary relation languages (like object oriented
languages and description logics), one typical way to represent
that a binary relation holds in some context is to "reify" the
relation-holding in the context as an object with a binary relation
between the obtainment and each the two relation arguments and a
third binary relation between the obtainment and an object
representing the context itself. The downside to this approach is
the expressive ability of the language to describe the binary
relation, especially in the case of description logics, is lost. One
can of course use RDF reification, however this is not supported
in OWL, either.
The motivation for context slices is to provide a logical pattern for
encoding context information in standard RDF graphs that allows
some of the expressiveness of OWL to be used in describing the
relations that hold in contexts.
This is a generalization of the four dimensional ontology for
fluents published in [1].
2. PATTERN DESCRIPTION
The idea of the context slices pattern is, rather than reifying the Figure 1: Graphical illustration of an example using the pattern.
statement itself, to create a projection of the ''relation arguments''
in each context for which some binary relation holds between
them.
Take for example the statement "Chris believes Sam is CEO of 3. IMPLEMENTATION
IBM". Say we already have nodes in some graph representing In OWL functional syntax:
Sam, Chris and IBM. We create, as shown in Figure 1, the
context c1 corresponding to Chris' belief, and two nodes Ontology(
representing Chris' belief about Sam and Chris' belief about IBM Annotation(owl:versionInfo "1.0"@en)
(shown as Sam@c1 and IBM@c1). Annotation(rdfs:label "Context slices ontology logical
pattern"@en)
ObjectPropertyDomain(cs:hasContext
Declaration(Class(cs:Context)) cs:ContextualProjection)
DisjointClasses(cs:Context cs:ContextualProjection) Declaration(ObjectProperty(cs:projectionOf))
Declaration(Class(cs:ContextualProjection)) FunctionalObjectProperty(cs:projectionOf)
SubClassOf(cs:ContextualProjection ObjectPropertyDomain(cs:projectionOf
ObjectAllValuesFrom(cs:hasContext cs:Context)) cs:ContextualProjection))
SubClassOf(cs:ContextualProjection
ObjectExactCardinality(1 cs:hasContext))
SubClassOf(cs:ContextualProjection 4. REFERENCES
ObjectExactCardinality(1 cs:projectionOf)) [1] Welty, Chris and Richard E. Fikes. 2006. A Reusable
DisjointClasses(cs:ContextualProjection cs:Context) Ontology for Fluents in OWL. In Bennet and Fellbaum, eds.,
Declaration(ObjectProperty(cs:contextualProperty)) Proceedings of the Fourth International Conference on
ObjectPropertyDomain(cs:contextualProperty Formal Ontology in Information Systems. IOS Press. See
cs:ContextualProjection) http://www.booksonline.iospress.nl/Content/View.aspx?piid
ObjectPropertyRange(cs:contextualProperty =2209.
cs:ContextualProjection)
Declaration(ObjectProperty(cs:hasContext))
FunctionalObjectProperty(cs:hasContext)