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


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