denotation as a two-step mapping in semantic web architecture david booth, ph.d. cleveland clinic...

Denotation as a Two-Step Mapping in Semantic Web Architecture

David Booth, Ph.D.

Cleveland Clinic (contractor)

Identity Workshop, IJCAI 2009, Pasadena

11-July-2009

Latest version of these slides:

http://dbooth.org/2009/denotation/slides.pptCompanion paper: http://dbooth.org/2009/denotation/

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About the speaker

• Senior Software Architect, Cleveland Clinic's SemanticDB project

• Senior research architect, HP Software

– W3C GRDDL standard

– W3C Semantic Web Best Practices and Deployment group

• W3C Fellow 2002-2005

– W3C Web Services Architecture document

– W3C WSDL 2.0 standard

• AT&T Bell Labs

• Ph.D. Computer Science, UCLA

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Outline

• PART 1: Brief review of RDF Semantics

• PART 2: Two-step mapping

• PART 3: Conclusions

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PART 1

Brief Review of RDF Semantics

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URIs as names

URI

http://example#apple

Real worldinterpretation

• W3C Architecture of the World Wide Web: “a URI identifies one resource”

• RDF Semantics: an interpretation maps a URI to a

resource

?

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RDF Semantics

• W3C standard

• Defines the semantics of a given RDF graph in

terms of possible interpretations

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Interpretations in RDF Semantics

• An interpretation maps each URI in the graph to a resource

– A resource may be anything

• A given RDF graph may admit many possible

interpretations

• RDF Semantics describes how the set of possible

interpretations for that graph is constrained

• Empty set of possible interpretations means the

graph cannot be satisfied

– I.e., assertions are contradictory

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Effect of adding assertions to an RDF graph

• Set of possible interpretations is reduced monotonically

Set ofPossible RDFinterpretations





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Interpretations map URIs to resources

• Each interpretation may map the URI to a different resource


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Interpretations for a URI

For brevity: “Interpretations for the URI” == the set of resources corresponding to the set of possible interpretations


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Adding assertions reduces the set of possible interpretations

• E.g., by merging RDF graphs, constraints of both

graphs must be satisfied


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Effect of owl:sameAs

• X owl:sameAs Y

• Each URI has a set of possible interpretations

• owl:sameAs limits this set to the intersection

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Inconsistent combined graphs

• URI X is used in graphs A, B and C

• A+B is consistent

• A+C is consistent

• A+B+C is not consistent – requires splitting X into two URIs:

– One for the the intersection of A+B, the other for the intersection

of B+C

B A C

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RDF semantics for an application

Available assertions

e.g. <http://example#apple> ...

1. Selectassertions

1.a. Get ontologies

Semantic extensionse.g. OWL, FruitOnt

e.g. rdf:comment " ... " .

Informalassertions

3. Select aninterpretation

2. ApplyRDF+extensionsemantics

Formalassertions Possible interpretations

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PART 2

Two-Step Mapping

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How are URIs mapped to resources?

URI


Real worldinterpretation?

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Denotation as a two-step mapping from URI to resource

URI


Set of assertionsfrom URI declaration

Step 1

<http://example#apple :foo :bar . . . .

Real worldinterpretation

Step 2

• How does view this fit with RDF semantics? Let's see . . .

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URI declaration

• Defines a set of core assertions whose purpose is

to constrain the interpretation of a URI

• Anchors the “meaning” of the URI

• Normally provided by URI owner

– E.g., at follow-your-nose location

• See: http://dbooth.org/2007/uri-decl/

http://dbooth.org/2007/uri-decl/

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Selecting interpretations in two steps

1. Selectassertions



Possible interpretations


Informalassertions


Formalassertions


1.a. Get ontologies

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Selecting interpretations in two steps

1. Selectassertions





Informalassertions


Formalassertions


1.a. Get ontologies

3.b. Select aninterpretation

3.a. Apply constraintsfrom URI declarations


3.

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Getting URI declarations as ontologies

1. Selectassertions






Informalassertions


Formalassertions


1.a. Get ontologies& URI declarations

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PART 3

Conclusions

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Conclusions

• This view of denotation as a two-step mapping:

– Consistent with RDF Semantics

– Helps explain how resource identity can be established

• A URI denotes one resource . . .

– But that resource depends on the interpretation

• URI maps to a cloud of possible resources

– The possibilities are precisely constrained by the core

assertions in a URI's declaration

• “X owl:sameAs Y” does not require that X and Y's

clouds of possible resources are the same!

– It limits the interpretations to the intersection

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More information

• Denotation as a Two-Step Mapping:http://dbooth.org/2009/denotation/

• URI declarations:


• URI lifecycle:

http://dbooth.org/2009/lifecycle/

http://dbooth.org/2009/denotation/


http://dbooth.org/2009/lifecycle/

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Questions?

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Parking Lot

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httpRange-14

• “Should http URIs be used for non-information

resources?” (Paraphrased)

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Figure @@: RDF semantics for an application

1. Selectassertions






Informalassertions


Formalassertions


1.a. Get ontologies& URI declarations

3.b. Select aninterpretation

3.a. Apply constraintsfrom URI declarations


3.

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PART 1

The Problem

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Problem 1: Babelization

• Proliferation of data models (XML schemas, etc.)

• Parsing issues influence data

models

• No consistent semantics

• Data chaos

Tower of Babel, Abel Grimmer (1570-1619)

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PART 3

Example: Cleveland Clinic SemanticDB

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SemanticDB Project

• Applies semantic web technology to:– Clinical research

– Outcomes reporting

– Quality reporting

• Sponsored by Cleveland Clinic's Heart and Vascular

Institute

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Cleveland Clinic SemanticDB Project

SPARQL interfaceSPARQL interface

Patientregistry

Geneticpatientregistry

Tagged literature,e.g.,

PUBMED

Cycnatural language

processing

Patient-centric systems

Semantic wiki

Structured query

Natural languagequery

Instance data

User interfaces

. . .

Data-source adaptorsData-source adaptors

SemanticDataFederation

Gene Ontology (GO)

Ontology of Medicine

Domain-specific Ontologies

Data-source Ontologies

SQL,SPARQL

Cycupper

ontology

Ontologies

. . .

Patient Data Entry

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Adding assertions to an RDF graph



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“Interpretations” as resources

• For a given URI, each interpretation maps that URI to a potentially different resource

• There defines a corresponding set of resources

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Effect of adding assertions to an RDF graph






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Interpretations for an RDF graph


denotation as a two-step mapping in semantic web architecture david booth, ph.d. cleveland clinic...

Documents

rdf semanticsan interpretation

given rdf graph

merging rdf graphs

set of resources

uri ownere

set of core assertions

sameas yeach uri

resourceseach interpretation