multi-agent semantic web systems: rdf data structures · multi-agent semantic web systems: rdf data...
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Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Multi-agent Semantic Web Systems:RDF Data Structures
Ewan Klein
MASWS — 25 January 2008
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
1 Review: RDF Basic ConceptsRDF Graphs and Triples
2 Structured ValuesIntermediary NodesBlank NodesN-ary RelationsContainers
3 Digression on N3
4 RDFS
5 Summary
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Admin stuff
Tutorial:
Tuesday 29 Jan 2008
1:00-2:00
Room 5.08 AT
Assignment:
I will update the RDFS section and add more details, plusmarking scheme.
Hopefully by Monday 28th (Jan)
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Admin stuff
Tutorial:
Tuesday 29 Jan 2008
1:00-2:00
Room 5.08 AT
Assignment:
I will update the RDFS section and add more details, plusmarking scheme.
Hopefully by Monday 28th (Jan)
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
RDF Data Model, 1
Two kinds of triple in RDF:
edstaff:9888 'Ewan Klein' foaf:name
infcourses:masws edstaff:9888dc:creator
subject predicate object
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
RDF Data Model, 1
Two kinds of triple in RDF:
edstaff:9888 'Ewan Klein' foaf:name
infcourses:masws edstaff:9888dc:creator
subject predicate object
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
RDF Data Model, 2
'Ewan Klein'
foaf:name
infcourses:masws
edstaff:9888
dc:creator
object
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
RDF Data Model, 2
'Ewan Klein'
foaf:name
infcourses:masws
edstaff:9888
dc:creator
subject
predicate
object
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
RDF Data Model, 2
'Ewan Klein'
foaf:name
infcourses:masws
edstaff:9888
dc:creator
subject
predicate
subject
object
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
URIs and QNames
An RDF vocabulary is a set of URIs, not words.
We use QNames as an abbreviatory convention for URIs.
1 Associate a prefix with a URI;2 follow it with a colon (‘:’) and a local name
Some PrefixesPrefix Namespace URI
edstaff http://www.ed.ac.uk/staffid#dc http://purl.org/dc/elements/1.1/
Example QNames
edstaff:9888dc:creator
Example RDF Triples
infcourses:masws dc:creator edstaff:9888 .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
URIs and QNames
An RDF vocabulary is a set of URIs, not words.We use QNames as an abbreviatory convention for URIs.
1 Associate a prefix with a URI;2 follow it with a colon (‘:’) and a local name
Some PrefixesPrefix Namespace URI
edstaff http://www.ed.ac.uk/staffid#dc http://purl.org/dc/elements/1.1/
Example QNames
edstaff:9888dc:creator
Example RDF Triples
infcourses:masws dc:creator edstaff:9888 .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
URIs and QNames
An RDF vocabulary is a set of URIs, not words.We use QNames as an abbreviatory convention for URIs.
1 Associate a prefix with a URI;
2 follow it with a colon (‘:’) and a local name
Some PrefixesPrefix Namespace URI
edstaff http://www.ed.ac.uk/staffid#dc http://purl.org/dc/elements/1.1/
Example QNames
edstaff:9888dc:creator
Example RDF Triples
infcourses:masws dc:creator edstaff:9888 .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
URIs and QNames
An RDF vocabulary is a set of URIs, not words.We use QNames as an abbreviatory convention for URIs.
1 Associate a prefix with a URI;2 follow it with a colon (‘:’) and a local name
Some PrefixesPrefix Namespace URI
edstaff http://www.ed.ac.uk/staffid#dc http://purl.org/dc/elements/1.1/
Example QNames
edstaff:9888dc:creator
Example RDF Triples
infcourses:masws dc:creator edstaff:9888 .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
URIs and QNames
An RDF vocabulary is a set of URIs, not words.We use QNames as an abbreviatory convention for URIs.
1 Associate a prefix with a URI;2 follow it with a colon (‘:’) and a local name
Some PrefixesPrefix Namespace URI
edstaff http://www.ed.ac.uk/staffid#dc http://purl.org/dc/elements/1.1/
Example QNames
edstaff:9888dc:creator
Example RDF Triples
infcourses:masws dc:creator edstaff:9888 .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
URIs and QNames
An RDF vocabulary is a set of URIs, not words.We use QNames as an abbreviatory convention for URIs.
1 Associate a prefix with a URI;2 follow it with a colon (‘:’) and a local name
Some PrefixesPrefix Namespace URI
edstaff http://www.ed.ac.uk/staffid#dc http://purl.org/dc/elements/1.1/
Example QNames
edstaff:9888dc:creator
Example RDF Triples
infcourses:masws dc:creator edstaff:9888 .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Structured Values, 1
So far, a value is always a resource or a literal.
How do we deal with structured values?
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Structured Values, 1
So far, a value is always a resource or a literal.
How do we deal with structured values?
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Structured Values, 2
Example: Complex value as a string
meals:lunch06 meals:mainCourse ’beef, peas, rice’ .
Using a string doesn’t allow us to look at the parts of acomplex value.
Wrong
meals:lunch06 meals:mainCourse ’beef’ .meals:lunch06 meals:mainCourse ’peas’ .meals:lunch06 meals:mainCourse ’rice’ .
We don’t really want to say that beef, peas and rice arethemselves main courses;
they are parts of a main course.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Structured Values, 2
Example: Complex value as a string
meals:lunch06 meals:mainCourse ’beef, peas, rice’ .
Using a string doesn’t allow us to look at the parts of acomplex value.
Wrong
meals:lunch06 meals:mainCourse ’beef’ .meals:lunch06 meals:mainCourse ’peas’ .meals:lunch06 meals:mainCourse ’rice’ .
We don’t really want to say that beef, peas and rice arethemselves main courses;
they are parts of a main course.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Structured Values, 2
Example: Complex value as a string
meals:lunch06 meals:mainCourse ’beef, peas, rice’ .
Using a string doesn’t allow us to look at the parts of acomplex value.
Wrong
meals:lunch06 meals:mainCourse ’beef’ .meals:lunch06 meals:mainCourse ’peas’ .meals:lunch06 meals:mainCourse ’rice’ .
We don’t really want to say that beef, peas and rice arethemselves main courses;
they are parts of a main course.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Structured Values, 2
Example: Complex value as a string
meals:lunch06 meals:mainCourse ’beef, peas, rice’ .
Using a string doesn’t allow us to look at the parts of acomplex value.
Wrong
meals:lunch06 meals:mainCourse ’beef’ .meals:lunch06 meals:mainCourse ’peas’ .meals:lunch06 meals:mainCourse ’rice’ .
We don’t really want to say that beef, peas and rice arethemselves main courses;
they are parts of a main course.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Aggregate Resource
Example of Aggregate Resource
meals:lunch06 meals:mainCourse meals:mainCourse10.
meals:mainCourse10 terms:meatPart ’beef’ .meals:mainCourse10 terms:vegPart ’peas’ .meals:mainCourse10 terms:starchPart ’rice’ .
lunch06 mainCourse10mainCourse 'peas'
'beef'
'rice'
meatPart
vegPart
starchPart
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Aggregate Resource
Example of Aggregate Resource
meals:lunch06 meals:mainCourse meals:mainCourse10.meals:mainCourse10 terms:meatPart ’beef’ .
meals:mainCourse10 terms:vegPart ’peas’ .meals:mainCourse10 terms:starchPart ’rice’ .
lunch06 mainCourse10mainCourse 'peas'
'beef'
'rice'
meatPart
vegPart
starchPart
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Aggregate Resource
Example of Aggregate Resource
meals:lunch06 meals:mainCourse meals:mainCourse10.meals:mainCourse10 terms:meatPart ’beef’ .meals:mainCourse10 terms:vegPart ’peas’ .
meals:mainCourse10 terms:starchPart ’rice’ .
lunch06 mainCourse10mainCourse 'peas'
'beef'
'rice'
meatPart
vegPart
starchPart
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Aggregate Resource
Example of Aggregate Resource
meals:lunch06 meals:mainCourse meals:mainCourse10.meals:mainCourse10 terms:meatPart ’beef’ .meals:mainCourse10 terms:vegPart ’peas’ .meals:mainCourse10 terms:starchPart ’rice’ .
lunch06 mainCourse10mainCourse 'peas'
'beef'
'rice'
meatPart
vegPart
starchPart
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Aggregate Resource
Example of Aggregate Resource
meals:lunch06 meals:mainCourse meals:mainCourse10.meals:mainCourse10 terms:meatPart ’beef’ .meals:mainCourse10 terms:vegPart ’peas’ .meals:mainCourse10 terms:starchPart ’rice’ .
lunch06 mainCourse10mainCourse 'peas'
'beef'
'rice'
meatPart
vegPart
starchPart
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Blank Nodes
We don’t necessarily want to create a new resource (suchas meals:mainCourse10) to name the aggregatestructure.
Relevant node in the graph could have been left blank:
lunch06 mainCourse 'peas'
'beef'
'rice'
meatPart
vegPart
starchPart
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Blank Nodes
We don’t necessarily want to create a new resource (suchas meals:mainCourse10) to name the aggregatestructure.
Relevant node in the graph could have been left blank:
lunch06 mainCourse 'peas'
'beef'
'rice'
meatPart
vegPart
starchPart
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Blank Nodes
We don’t necessarily want to create a new resource (suchas meals:mainCourse10) to name the aggregatestructure.
Relevant node in the graph could have been left blank:
lunch06 mainCourse 'peas'
'beef'
'rice'
meatPart
vegPart
starchPart
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Blank Nodes, 2
How do we represent blank nodes in N3 triples?
Blank node identifiers (also called anonymous resources)are of the form _:label
Example of Blank Node Identifier
meals:lunch06 meals:mainCourse _:a ._:a terms:meatPart ’beef’ ._:a terms:vegPart ’peas’ ._:a terms:starchPart ’rice’ .
Blank node identifiers are not intended to be globallyunique;
only unique relative to a single ‘graph’.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Blank Nodes, 2
How do we represent blank nodes in N3 triples?
Blank node identifiers (also called anonymous resources)are of the form _:label
Example of Blank Node Identifier
meals:lunch06 meals:mainCourse _:a ._:a terms:meatPart ’beef’ ._:a terms:vegPart ’peas’ ._:a terms:starchPart ’rice’ .
Blank node identifiers are not intended to be globallyunique;
only unique relative to a single ‘graph’.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Blank Nodes, 2
How do we represent blank nodes in N3 triples?
Blank node identifiers (also called anonymous resources)are of the form _:label
Example of Blank Node Identifier
meals:lunch06 meals:mainCourse _:a ._:a terms:meatPart ’beef’ ._:a terms:vegPart ’peas’ ._:a terms:starchPart ’rice’ .
Blank node identifiers are not intended to be globallyunique;
only unique relative to a single ‘graph’.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Blank Nodes, 2
How do we represent blank nodes in N3 triples?
Blank node identifiers (also called anonymous resources)are of the form _:label
Example of Blank Node Identifier
meals:lunch06 meals:mainCourse _:a ._:a terms:meatPart ’beef’ ._:a terms:vegPart ’peas’ ._:a terms:starchPart ’rice’ .
Blank node identifiers are not intended to be globallyunique;
only unique relative to a single ‘graph’.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Blank Nodes, 2
How do we represent blank nodes in N3 triples?
Blank node identifiers (also called anonymous resources)are of the form _:label
Example of Blank Node Identifier
meals:lunch06 meals:mainCourse _:a ._:a terms:meatPart ’beef’ ._:a terms:vegPart ’peas’ ._:a terms:starchPart ’rice’ .
Blank node identifiers are not intended to be globallyunique;
only unique relative to a single ‘graph’.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
When we can’t find a good URI
Even without aggregates, difficult to find URIs for manyresources.
Which URI would be ‘canonical’ for Ali Farka Toure?http://en.wikipedia.org/wiki/Ali Farka Toure
http://africanmusic.org/artists/alifarka.html
Some objects are just too ephemeral or not worth coiningidentifiers for:
the glass of red wine that I drank last nightthe car that almost ran into my bike this morningthe file transfer that was initiated when I checked in a copyof this lecture to the CVS repository
Alternative: represent resources via a cluster of ‘definitive’properties, using a blank node.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
When we can’t find a good URI
Even without aggregates, difficult to find URIs for manyresources.
Which URI would be ‘canonical’ for Ali Farka Toure?http://en.wikipedia.org/wiki/Ali Farka Toure
http://africanmusic.org/artists/alifarka.html
Some objects are just too ephemeral or not worth coiningidentifiers for:
the glass of red wine that I drank last nightthe car that almost ran into my bike this morningthe file transfer that was initiated when I checked in a copyof this lecture to the CVS repository
Alternative: represent resources via a cluster of ‘definitive’properties, using a blank node.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
When we can’t find a good URI
Even without aggregates, difficult to find URIs for manyresources.
Which URI would be ‘canonical’ for Ali Farka Toure?http://en.wikipedia.org/wiki/Ali Farka Toure
http://africanmusic.org/artists/alifarka.html
Some objects are just too ephemeral or not worth coiningidentifiers for:
the glass of red wine that I drank last nightthe car that almost ran into my bike this morningthe file transfer that was initiated when I checked in a copyof this lecture to the CVS repository
Alternative: represent resources via a cluster of ‘definitive’properties, using a blank node.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
When we can’t find a good URI
Even without aggregates, difficult to find URIs for manyresources.
Which URI would be ‘canonical’ for Ali Farka Toure?http://en.wikipedia.org/wiki/Ali Farka Toure
http://africanmusic.org/artists/alifarka.html
Some objects are just too ephemeral or not worth coiningidentifiers for:
the glass of red wine that I drank last night
the car that almost ran into my bike this morningthe file transfer that was initiated when I checked in a copyof this lecture to the CVS repository
Alternative: represent resources via a cluster of ‘definitive’properties, using a blank node.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
When we can’t find a good URI
Even without aggregates, difficult to find URIs for manyresources.
Which URI would be ‘canonical’ for Ali Farka Toure?http://en.wikipedia.org/wiki/Ali Farka Toure
http://africanmusic.org/artists/alifarka.html
Some objects are just too ephemeral or not worth coiningidentifiers for:
the glass of red wine that I drank last nightthe car that almost ran into my bike this morning
the file transfer that was initiated when I checked in a copyof this lecture to the CVS repository
Alternative: represent resources via a cluster of ‘definitive’properties, using a blank node.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
When we can’t find a good URI
Even without aggregates, difficult to find URIs for manyresources.
Which URI would be ‘canonical’ for Ali Farka Toure?http://en.wikipedia.org/wiki/Ali Farka Toure
http://africanmusic.org/artists/alifarka.html
Some objects are just too ephemeral or not worth coiningidentifiers for:
the glass of red wine that I drank last nightthe car that almost ran into my bike this morningthe file transfer that was initiated when I checked in a copyof this lecture to the CVS repository
Alternative: represent resources via a cluster of ‘definitive’properties, using a blank node.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
When we can’t find a good URI
Even without aggregates, difficult to find URIs for manyresources.
Which URI would be ‘canonical’ for Ali Farka Toure?http://en.wikipedia.org/wiki/Ali Farka Toure
http://africanmusic.org/artists/alifarka.html
Some objects are just too ephemeral or not worth coiningidentifiers for:
the glass of red wine that I drank last nightthe car that almost ran into my bike this morningthe file transfer that was initiated when I checked in a copyof this lecture to the CVS repository
Alternative: represent resources via a cluster of ‘definitive’properties, using a blank node.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Blank Nodes, 3
XY-33-53-60-C
'Kim'
mailto:[email protected]
name
natInsurNo
maibox
∃x .[name(x) = ”Kim”∧natInsurNo(x) = "XY-33-53-60-C" ∧mailbox(x) = mailto:[email protected]]
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Representing N-ary Relations in RDF
Not all relations are binary!
Examples of Relations with 3 Arguments
Livedoor shares fell by 14.4% on TuesdayJohn gave the flower to Sue
Two approaches(http://www.w3.org/TR/swbp-n-aryRelations):
1 Keep one argument as subject, and add an intermediarynode.
2 Make the relation into the subject node, and use ‘role’predicates.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Representing N-ary Relations in RDF
Not all relations are binary!
Examples of Relations with 3 Arguments
Livedoor shares fell by 14.4% on TuesdayJohn gave the flower to Sue
Two approaches(http://www.w3.org/TR/swbp-n-aryRelations):
1 Keep one argument as subject, and add an intermediarynode.
2 Make the relation into the subject node, and use ‘role’predicates.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Representing N-ary Relations in RDF
Not all relations are binary!
Examples of Relations with 3 Arguments
Livedoor shares fell by 14.4% on TuesdayJohn gave the flower to Sue
Two approaches(http://www.w3.org/TR/swbp-n-aryRelations):
1 Keep one argument as subject, and add an intermediarynode.
2 Make the relation into the subject node, and use ‘role’predicates.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Approach 1
livedoorShares fellRelation22fell
14%
2006-01-17
amount
date
livedoorShares is the subject of the statement.
fellRelation22 is a new intermediary node, allowing usto aggregate the percentage drop and the date.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Approach 2
giving1002 'flower'
'John'
'Sue'
donor
object
recipient
giving1002 is a specific instance of the giving relation.
The arguments of the relation are assigned named roles.
(Various proposals exist for what labels to assign to theseroles.)
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
RDF Containers
RDF defines a syntax for describing collections of resources:
bag: set with duplicates
sequence: ordered collection
alternative: alternative values
Also, collection, which is a closed container.Not discussed further right now.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
N3 Abbreviations
One subject, multiple properties
_:x foaf:name "Kim" ;foaf:mbox mailto:[email protected] .
_:x foaf:name "Kim" ._:x foaf:mbox mailto:[email protected] .
One subject, one predicate, multiple objects
ex:kim foaf:mbox mailto:[email protected] ,mailto:[email protected] .
ex:kim foaf:mbox mailto:[email protected] .ex:kim foaf:mbox mailto:[email protected] .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Ground Assertions
RDF allows us to make factual statements (assertions).
These statements are always about individual objects.
We can’t say things like the following:
Every page was created by some person.Dogs are mammals.Dogs bark.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Ground Assertions
RDF allows us to make factual statements (assertions).
These statements are always about individual objects.
We can’t say things like the following:
Every page was created by some person.Dogs are mammals.Dogs bark.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Ground Assertions
RDF allows us to make factual statements (assertions).
These statements are always about individual objects.
We can’t say things like the following:
Every page was created by some person.Dogs are mammals.Dogs bark.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Ground Assertions
RDF allows us to make factual statements (assertions).
These statements are always about individual objects.
We can’t say things like the following:
Every page was created by some person.
Dogs are mammals.Dogs bark.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Ground Assertions
RDF allows us to make factual statements (assertions).
These statements are always about individual objects.
We can’t say things like the following:
Every page was created by some person.Dogs are mammals.
Dogs bark.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Ground Assertions
RDF allows us to make factual statements (assertions).
These statements are always about individual objects.
We can’t say things like the following:
Every page was created by some person.Dogs are mammals.Dogs bark.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
No Semantic Constraints
By itself, RDF places no semantic restrictions on howpredicates combine with subjects and objects.
Even worse, RDF has no way of telling which URIs cansemantically act as predicates!
Anomalous Statements
infcourses:masws terms:knows edstaff:9888 .meals:lunch06 terms:homepage dc:title .mailto:[email protected] edstaff:9888 ’chicken’ .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
No Semantic Constraints
By itself, RDF places no semantic restrictions on howpredicates combine with subjects and objects.
Even worse, RDF has no way of telling which URIs cansemantically act as predicates!
Anomalous Statements
infcourses:masws terms:knows edstaff:9888 .meals:lunch06 terms:homepage dc:title .mailto:[email protected] edstaff:9888 ’chicken’ .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
No Semantic Constraints
By itself, RDF places no semantic restrictions on howpredicates combine with subjects and objects.
Even worse, RDF has no way of telling which URIs cansemantically act as predicates!
Anomalous Statements
infcourses:masws terms:knows edstaff:9888 .meals:lunch06 terms:homepage dc:title .mailto:[email protected] edstaff:9888 ’chicken’ .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
No Semantic Constraints
By itself, RDF places no semantic restrictions on howpredicates combine with subjects and objects.
Even worse, RDF has no way of telling which URIs cansemantically act as predicates!
Anomalous Statements
infcourses:masws terms:knows edstaff:9888 .
meals:lunch06 terms:homepage dc:title .mailto:[email protected] edstaff:9888 ’chicken’ .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
No Semantic Constraints
By itself, RDF places no semantic restrictions on howpredicates combine with subjects and objects.
Even worse, RDF has no way of telling which URIs cansemantically act as predicates!
Anomalous Statements
infcourses:masws terms:knows edstaff:9888 .meals:lunch06 terms:homepage dc:title .
mailto:[email protected] edstaff:9888 ’chicken’ .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
No Semantic Constraints
By itself, RDF places no semantic restrictions on howpredicates combine with subjects and objects.
Even worse, RDF has no way of telling which URIs cansemantically act as predicates!
Anomalous Statements
infcourses:masws terms:knows edstaff:9888 .meals:lunch06 terms:homepage dc:title .mailto:[email protected] edstaff:9888 ’chicken’ .
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
RDF Vocabulary Definition
RDF has been extended with mechanisms to allow newvocabularies to be defined.
Resulting language known as RDF Schema (RDFS; cf.http://www.w3.org/TR/rdf-schema/)
Basic idea is to allow statements like the following:
Example RDFS Constraints
The subject of ‘birthday’ must be an Agent.The object of ‘homepage’ must be a Document.Every instance of Person is an instance of Agent.
These vocabularies, and similar sets of definitions, arefrequently called ontologies.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
RDF Vocabulary Definition
RDF has been extended with mechanisms to allow newvocabularies to be defined.
Resulting language known as RDF Schema (RDFS; cf.http://www.w3.org/TR/rdf-schema/)
Basic idea is to allow statements like the following:
Example RDFS Constraints
The subject of ‘birthday’ must be an Agent.The object of ‘homepage’ must be a Document.Every instance of Person is an instance of Agent.
These vocabularies, and similar sets of definitions, arefrequently called ontologies.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
RDF Vocabulary Definition
RDF has been extended with mechanisms to allow newvocabularies to be defined.
Resulting language known as RDF Schema (RDFS; cf.http://www.w3.org/TR/rdf-schema/)
Basic idea is to allow statements like the following:
Example RDFS Constraints
The subject of ‘birthday’ must be an Agent.The object of ‘homepage’ must be a Document.Every instance of Person is an instance of Agent.
These vocabularies, and similar sets of definitions, arefrequently called ontologies.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
RDF Vocabulary Definition
RDF has been extended with mechanisms to allow newvocabularies to be defined.
Resulting language known as RDF Schema (RDFS; cf.http://www.w3.org/TR/rdf-schema/)
Basic idea is to allow statements like the following:
Example RDFS Constraints
The subject of ‘birthday’ must be an Agent.The object of ‘homepage’ must be a Document.Every instance of Person is an instance of Agent.
These vocabularies, and similar sets of definitions, arefrequently called ontologies.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
RDF Vocabulary Definition
RDF has been extended with mechanisms to allow newvocabularies to be defined.
Resulting language known as RDF Schema (RDFS; cf.http://www.w3.org/TR/rdf-schema/)
Basic idea is to allow statements like the following:
Example RDFS Constraints
The subject of ‘birthday’ must be an Agent.The object of ‘homepage’ must be a Document.Every instance of Person is an instance of Agent.
These vocabularies, and similar sets of definitions, arefrequently called ontologies.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Frame-based KR
isa and io links from frame-based knowledgerepresentation:
hasLegs 4Mammal
eats PlantHerbivore
eats AnimalCarnivore
LionGiraffe
Jerome Leo
isa isa
isa isa
io io
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Classes and Instances
Declaring Classes
terms:Giraffe rdf:type rdfs:Class .terms:Herbivore rdf:type rdfs:Class .
Giraffe and Herbivore are classes.
Instances
myzoo:gerome rdf:type terms:Giraffe .myzoo:gerome a terms:Giraffe .
jerome is an instance of (io) Giraffe.
Subclasses
terms:Giraffe rdfs:subClassOf terms:Herbivore .
Giraffe is a subclass of (isa) Herbivore.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Classes and Instances
Declaring Classes
terms:Giraffe rdf:type rdfs:Class .terms:Herbivore rdf:type rdfs:Class .
Giraffe and Herbivore are classes.
Instances
myzoo:gerome rdf:type terms:Giraffe .myzoo:gerome a terms:Giraffe .
jerome is an instance of (io) Giraffe.
Subclasses
terms:Giraffe rdfs:subClassOf terms:Herbivore .
Giraffe is a subclass of (isa) Herbivore.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Classes and Instances
Declaring Classes
terms:Giraffe rdf:type rdfs:Class .terms:Herbivore rdf:type rdfs:Class .
Giraffe and Herbivore are classes.
Instances
myzoo:gerome rdf:type terms:Giraffe .myzoo:gerome a terms:Giraffe .
jerome is an instance of (io) Giraffe.
Subclasses
terms:Giraffe rdfs:subClassOf terms:Herbivore .
Giraffe is a subclass of (isa) Herbivore.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Properties
Properties
terms:eats rdf:type rdf:Property .terms:eats a rdf:Property .
eats is a property.
Domain
terms:eats rdfs:domain terms:Animal .
The subjects of eats are instances of Animals.
Range
terms:eats rdfs:range terms:Plant .
The values of eats are instances of Plant.eats : Animal 7→ Plant
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Properties
Properties
terms:eats rdf:type rdf:Property .terms:eats a rdf:Property .
eats is a property.
Domain
terms:eats rdfs:domain terms:Animal .
The subjects of eats are instances of Animals.
Range
terms:eats rdfs:range terms:Plant .
The values of eats are instances of Plant.eats : Animal 7→ Plant
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Properties
Properties
terms:eats rdf:type rdf:Property .terms:eats a rdf:Property .
eats is a property.
Domain
terms:eats rdfs:domain terms:Animal .
The subjects of eats are instances of Animals.
Range
terms:eats rdfs:range terms:Plant .
The values of eats are instances of Plant.eats : Animal 7→ Plant
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 1
We can use intermediary nodes to aggregate a subset ofstatements.
Aggregates can be rooted in an ordinary resource node orin a blank node.
Blank nodes are referred to with a special namingconvention in triples: _:label.
Blank nodes can also be used for other things:
Referring to individuals via a cluster of properties.Expressing relations of arity > 2 (via two patterns).
RDF only allows us to make statements about individuals;no quantifiers, no general statements.
We need something richer on top of RDF to define whatcounts as ‘semantically well-formed’ statements ⇒ RDFS
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 1
We can use intermediary nodes to aggregate a subset ofstatements.
Aggregates can be rooted in an ordinary resource node orin a blank node.
Blank nodes are referred to with a special namingconvention in triples: _:label.
Blank nodes can also be used for other things:
Referring to individuals via a cluster of properties.Expressing relations of arity > 2 (via two patterns).
RDF only allows us to make statements about individuals;no quantifiers, no general statements.
We need something richer on top of RDF to define whatcounts as ‘semantically well-formed’ statements ⇒ RDFS
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 1
We can use intermediary nodes to aggregate a subset ofstatements.
Aggregates can be rooted in an ordinary resource node orin a blank node.
Blank nodes are referred to with a special namingconvention in triples: _:label.
Blank nodes can also be used for other things:
Referring to individuals via a cluster of properties.Expressing relations of arity > 2 (via two patterns).
RDF only allows us to make statements about individuals;no quantifiers, no general statements.
We need something richer on top of RDF to define whatcounts as ‘semantically well-formed’ statements ⇒ RDFS
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 1
We can use intermediary nodes to aggregate a subset ofstatements.
Aggregates can be rooted in an ordinary resource node orin a blank node.
Blank nodes are referred to with a special namingconvention in triples: _:label.
Blank nodes can also be used for other things:
Referring to individuals via a cluster of properties.Expressing relations of arity > 2 (via two patterns).
RDF only allows us to make statements about individuals;no quantifiers, no general statements.
We need something richer on top of RDF to define whatcounts as ‘semantically well-formed’ statements ⇒ RDFS
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 1
We can use intermediary nodes to aggregate a subset ofstatements.
Aggregates can be rooted in an ordinary resource node orin a blank node.
Blank nodes are referred to with a special namingconvention in triples: _:label.
Blank nodes can also be used for other things:
Referring to individuals via a cluster of properties.
Expressing relations of arity > 2 (via two patterns).
RDF only allows us to make statements about individuals;no quantifiers, no general statements.
We need something richer on top of RDF to define whatcounts as ‘semantically well-formed’ statements ⇒ RDFS
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 1
We can use intermediary nodes to aggregate a subset ofstatements.
Aggregates can be rooted in an ordinary resource node orin a blank node.
Blank nodes are referred to with a special namingconvention in triples: _:label.
Blank nodes can also be used for other things:
Referring to individuals via a cluster of properties.Expressing relations of arity > 2 (via two patterns).
RDF only allows us to make statements about individuals;no quantifiers, no general statements.
We need something richer on top of RDF to define whatcounts as ‘semantically well-formed’ statements ⇒ RDFS
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 1
We can use intermediary nodes to aggregate a subset ofstatements.
Aggregates can be rooted in an ordinary resource node orin a blank node.
Blank nodes are referred to with a special namingconvention in triples: _:label.
Blank nodes can also be used for other things:
Referring to individuals via a cluster of properties.Expressing relations of arity > 2 (via two patterns).
RDF only allows us to make statements about individuals;no quantifiers, no general statements.
We need something richer on top of RDF to define whatcounts as ‘semantically well-formed’ statements ⇒ RDFS
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 1
We can use intermediary nodes to aggregate a subset ofstatements.
Aggregates can be rooted in an ordinary resource node orin a blank node.
Blank nodes are referred to with a special namingconvention in triples: _:label.
Blank nodes can also be used for other things:
Referring to individuals via a cluster of properties.Expressing relations of arity > 2 (via two patterns).
RDF only allows us to make statements about individuals;no quantifiers, no general statements.
We need something richer on top of RDF to define whatcounts as ‘semantically well-formed’ statements ⇒ RDFS
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 2
RDF Schema (RDFS) provides mechanisms for describing(simple) ontologies.
RDFS built on top of RDF, using rdf:type.
Provides
Class, subClassOfProperty, subPropertyOfdomain, range
Deliberately not ‘object-oriented’
Classes are primitives, not defined in terms of necessaryand sufficient properties.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 2
RDF Schema (RDFS) provides mechanisms for describing(simple) ontologies.
RDFS built on top of RDF, using rdf:type.
Provides
Class, subClassOfProperty, subPropertyOfdomain, range
Deliberately not ‘object-oriented’
Classes are primitives, not defined in terms of necessaryand sufficient properties.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 2
RDF Schema (RDFS) provides mechanisms for describing(simple) ontologies.
RDFS built on top of RDF, using rdf:type.
Provides
Class, subClassOfProperty, subPropertyOfdomain, range
Deliberately not ‘object-oriented’
Classes are primitives, not defined in terms of necessaryand sufficient properties.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 2
RDF Schema (RDFS) provides mechanisms for describing(simple) ontologies.
RDFS built on top of RDF, using rdf:type.
Provides
Class, subClassOf
Property, subPropertyOfdomain, range
Deliberately not ‘object-oriented’
Classes are primitives, not defined in terms of necessaryand sufficient properties.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 2
RDF Schema (RDFS) provides mechanisms for describing(simple) ontologies.
RDFS built on top of RDF, using rdf:type.
Provides
Class, subClassOfProperty, subPropertyOf
domain, range
Deliberately not ‘object-oriented’
Classes are primitives, not defined in terms of necessaryand sufficient properties.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 2
RDF Schema (RDFS) provides mechanisms for describing(simple) ontologies.
RDFS built on top of RDF, using rdf:type.
Provides
Class, subClassOfProperty, subPropertyOfdomain, range
Deliberately not ‘object-oriented’
Classes are primitives, not defined in terms of necessaryand sufficient properties.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 2
RDF Schema (RDFS) provides mechanisms for describing(simple) ontologies.
RDFS built on top of RDF, using rdf:type.
Provides
Class, subClassOfProperty, subPropertyOfdomain, range
Deliberately not ‘object-oriented’
Classes are primitives, not defined in terms of necessaryand sufficient properties.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Summary, 2
RDF Schema (RDFS) provides mechanisms for describing(simple) ontologies.
RDFS built on top of RDF, using rdf:type.
Provides
Class, subClassOfProperty, subPropertyOfdomain, range
Deliberately not ‘object-oriented’
Classes are primitives, not defined in terms of necessaryand sufficient properties.
Multi-agentSemantic Web
Systems:RDF DataStructures
Ewan Klein
Outline
Review: RDFBasicConcepts
RDF Graphs andTriples
StructuredValues
IntermediaryNodes
Blank Nodes
N-ary Relations
Containers
Digression onN3
RDFS
Summary
Reading
RDF in general
Passin: Chapter 2 (on RDF)
W3C RDF Primer http://www.w3.org/TR/rdf-primer/
N3 / Turtle
N3 Primer: http://www.w3.org/2000/10/swap/Primer
Turtle: http://www.dajobe.org/2004/01/turtle/