Submissions:Context Slices
From Odp
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We can express relation taxonomies in the usual way. This is tricky to do using reified obtainments, though it is possible. | We can express relation taxonomies in the usual way. This is tricky to do using reified obtainments, though it is possible. | ||
|Elements=As shown in the diagram, the pattern uses two predefined classes, cs:ContextualProjection and cs:Context. It uses two predefined properties, cs:projectionOf (ContextualProjection x TOP), and cs:hasContext (cs:ContextualProjection x cs:Context). Properties that hold in a context can extend the property cs:contextualProperty. | |Elements=As shown in the diagram, the pattern uses two predefined classes, cs:ContextualProjection and cs:Context. It uses two predefined properties, cs:projectionOf (ContextualProjection x TOP), and cs:hasContext (cs:ContextualProjection x cs:Context). Properties that hold in a context can extend the property cs:contextualProperty. | ||
| - | |Implementation=<?xml version="1.0" encoding="UTF-8"?> | + | |Implementation=In OWL functional syntax: |
| + | Prefix(xsd:=<http://www.w3.org/2001/XMLSchema#>) | ||
| + | Prefix(rdfs:=<http://www.w3.org/2000/01/rdf-schema#>) | ||
| + | Prefix(owl:=<http://www.w3.org/2002/07/owl#>) | ||
| + | Prefix(cs:=<http://example.org/ContextSlices#>) | ||
| + | |||
| + | Ontology(<http://example.org/ContextSlices> | ||
| + | Annotation(owl:versionInfo "1.0"@en) | ||
| + | Annotation(rdfs:label "Context slices ontology logical pattern"@en) | ||
| + | |||
| + | Declaration(Class(cs:Context)) | ||
| + | DisjointClasses(cs:Context cs:ContextualProjection) | ||
| + | Declaration(Class(cs:ContextualProjection)) | ||
| + | SubClassOf(cs:ContextualProjection ObjectAllValuesFrom(cs:hasContext cs:Context)) | ||
| + | SubClassOf(cs:ContextualProjection ObjectExactCardinality(1 cs:hasContext)) | ||
| + | SubClassOf(cs:ContextualProjection ObjectExactCardinality(1 cs:projectionOf)) | ||
| + | DisjointClasses(cs:ContextualProjection cs:Context) | ||
| + | Declaration(ObjectProperty(cs:contextualProperty)) | ||
| + | ObjectPropertyDomain(cs:contextualProperty cs:ContextualProjection) | ||
| + | ObjectPropertyRange(cs:contextualProperty cs:ContextualProjection) | ||
| + | Declaration(ObjectProperty(cs:hasContext)) | ||
| + | FunctionalObjectProperty(cs:hasContext) | ||
| + | ObjectPropertyDomain(cs:hasContext cs:ContextualProjection) | ||
| + | Declaration(ObjectProperty(cs:projectionOf)) | ||
| + | FunctionalObjectProperty(cs:projectionOf) | ||
| + | ObjectPropertyDomain(cs:projectionOf cs:ContextualProjection) | ||
| + | ) | ||
| + | |||
| + | In RDF/XML: | ||
| + | |||
| + | <?xml version="1.0" encoding="UTF-8"?> | ||
<!DOCTYPE rdf:RDF [ | <!DOCTYPE rdf:RDF [ | ||
<!ENTITY owl "http://www.w3.org/2002/07/owl#"> | <!ENTITY owl "http://www.w3.org/2002/07/owl#"> | ||
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The context defines the contextual extent of the slice. If any relations hold in a context, they | The context defines the contextual extent of the slice. If any relations hold in a context, they | ||
must be to other slices of the same context (there is no way to enforce this constraint in OWL). | must be to other slices of the same context (there is no way to enforce this constraint in OWL). | ||
| - | <rdfs:comment> | + | </rdfs:comment> |
<rdfs:subClassOf> | <rdfs:subClassOf> | ||
<owl:Restriction> | <owl:Restriction> | ||
Revision as of 02:24, 20 August 2010
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Graphical representation
Diagram
General information
| Name | Context Slices |
|---|---|
| Also known as | |
| Author(s) | Chris Welty |
| SubmittedBy | Chris Welty |
Description
| Motivation | Most information on the web is contextualized somehow, for example information may be believed by a person or organization, it may hold only for some time period, it may have been reported/observed by an individual, etc. There are myriad proposals and logics for context, but none are standards and few have even prototype implementations.
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 (sometimes called obtainment) 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. 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 generaliztion of the four dimensional ontology for fluents published in [Welty & Fikes, 2006]. |
|---|---|
| Aim | To encode that a binary relation holds in a context. |
| Solution description | As shown in the example, the idea of the context slices pattern is, rather than reifying the obtainment 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 IBM". Say we already have nodes in some graph representing Sam and IBM. We create, as shown in the diagram, the context c1 corresponding to Chris' belief, and two nodes representing Chris' belief about Sam and Chris' belief about IBM (shown as Sam@c1 and IBM@c1). This allows us to represent ceoOf as a binary relation, which seems more natural, and it allows us to use the expressivity of OWL in more ways. We can say of the ceoOf relation that it has an inverse, hasCeo. In contrast, the reified obtainment approach has no "directionality" in relations, but rather represents the "roles" played by the arguments as binary relations to the obtainment. We can express cardinality, e.g. a company may have only one CEO within a context. This axiom cannot be expressed in OWL for reified obtainments. We can say that a relation is transitive or symmetric. Symmetry can be expressed in reified obtainments by using a single role for both arguments, but not transitivity. We can express relation taxonomies in the usual way. This is tricky to do using reified obtainments, though it is possible. |
| Elements | As shown in the diagram, the pattern uses two predefined classes, cs:ContextualProjection and cs:Context. It uses two predefined properties, cs:projectionOf (ContextualProjection x TOP), and cs:hasContext (cs:ContextualProjection x cs:Context). Properties that hold in a context can extend the property cs:contextualProperty. |
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Example
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| Pattern solution example | |
| Consequences |
Pattern reference
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| Reference | |
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| Test |
Additional information
Scenarios
No scenario is added to this Content OP.
Reviews
| Review article | Posted on | About revision (current is 9846) |
|---|---|---|
| VojtechSvatek about Context Slices | 245545616 September 2010 | 1005810,058 |
| ValentinaPresutti about Context Slices | 245546323 September 2010 | 1011910,119 |
| EnricoMotta about Context Slices | 245545919 September 2010 | 1011910,119 |
This revision (revision ID 9846) takes in account the reviews: ValentinaPresutti about Context Slices
Other info at evaluation tab
Modeling issues
There is no Modeling issue related to this proposal.
References
