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: Companion paper:

2 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 – W3C Web Services Architecture document – W3C WSDL 2.0 standard AT&T Bell Labs Ph.D. Computer Science, UCLA

3 Outline PART 1: Brief review of RDF Semantics PART 2: Two-step mapping PART 3: Conclusions

4 PART 1 Brief Review of RDF Semantics

5 URIs as names URI Real world interpretation W3C Architecture of the World Wide Web: “a URI identifies one resource” RDF Semantics: an interpretation maps a URI to a resource ?

6 RDF Semantics W3C standard Defines the semantics of a given RDF graph in terms of possible interpretations

7 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

8 Effect of adding assertions to an RDF graph Set of possible interpretations is reduced monotonically Set of Possible RDF interpretations

9 Interpretations map URIs to resources Each interpretation may map the URI to a different resource

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

11 Adding assertions reduces the set of possible interpretations E.g., by merging RDF graphs, constraints of both graphs must be satisfied

12 Effect of owl:sameAs X owl:sameAs Y Each URI has a set of possible interpretations owl:sameAs limits this set to the intersection

13 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 BAC

14 RDF semantics for an application Available assertions e.g Select assertions 1.a. Get ontologies Semantic extensions e.g. OWL, FruitOnt e.g. rdf:comment "... ". Informal assertions 3. Select an interpretation 2. Apply RDF+extension semantics Formal assertions Possible interpretations

15 PART 2 Two-Step Mapping

16 How are URIs mapped to resources? URI Real world interpretation ?

17 Denotation as a two-step mapping from URI to resource URI Set of assertions from URI declaration Step 1 < :foo :bar.... Real world interpretation Step 2 How does view this fit with RDF semantics? Let's see...

18 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:

19 3. Select an interpretation Selecting interpretations in two steps 1. Select assertions 2. Apply RDF+extension semantics Available assertions Possible interpretations e.g.... Informal assertions e.g. rdf:comment "... ". Formal assertions Semantic extensions e.g. OWL, FruitOnt 1.a. Get ontologies

20 Selecting interpretations in two steps 1. Select assertions 2. Apply RDF+extension semantics Available assertions Possible interpretations e.g.... Informal assertions e.g. rdf:comment "... ". Formal assertions Semantic extensions e.g. OWL, FruitOnt 1.a. Get ontologies 3.b. Select an interpretation 3.a. Apply constraints from URI declarations Possible interpretations 3.

21 Getting URI declarations as ontologies 1. Select assertions 3. Select an interpretation 2. Apply RDF+extension semantics Available assertions Possible interpretations e.g.... Informal assertions e.g. rdf:comment "... ". Formal assertions Semantic extensions e.g. OWL, FruitOnt 1.a. Get ontologies & URI declarations

22 PART 3 Conclusions

23 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

24 More information Denotation as a Two-Step Mapping: URI declarations: URI lifecycle:

25 Questions?

26 Parking Lot

27 httpRange-14 “Should http URIs be used for non-information resources?” (Paraphrased)

28 Figure RDF semantics for an application 1. Select assertions 3. Select an interpretation 2. Apply RDF+extension semantics Available assertions Possible interpretations e.g.... Informal assertions e.g. rdf:comment "... ". Formal assertions Semantic extensions e.g. OWL, FruitOnt 1.a. Get ontologies & URI declarations 3.b. Select an interpretation 3.a. Apply constraints from URI declarations Possible interpretations 3.

29 PART 1 The Problem

30 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 ( )

31 PART 3 Example: Cleveland Clinic SemanticDB

32 SemanticDB Project Applies semantic web technology to: – Clinical research – Outcomes reporting – Quality reporting Sponsored by Cleveland Clinic's Heart and Vascular Institute

33 Cleveland Clinic SemanticDB Project SPARQL interface Patient registry Genetic patient registry Tagged literature, e.g., PUBMED Cyc natural language processing Patient-centric systems Semantic wiki Structured query Natural language query Instance data User interfaces... Data-source adaptors Semantic Data Federation Gene Ontology (GO) Ontology of Medicine Domain-specific Ontologies Data-source Ontologies SQL, SPARQL Cyc upper ontology Ontologies... Patient Data Entry

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37 Adding assertions to an RDF graph Set of possible interpretations is reduced monotonically

38 Adding assertions to an RDF graph Set of possible interpretations is reduced monotonically

39 Adding assertions to an RDF graph Set of possible interpretations is reduced monotonically Possible interpretations

40 Adding assertions to an RDF graph Set of possible interpretations is reduced monotonically Possible interpretations

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42 Adding assertions to an RDF graph Set of possible interpretations is reduced monotonically

43 “Interpretations” as resources For a given URI, each interpretation maps that URI to a potentially different resource There defines a corresponding set of resources

44 Effect of adding assertions to an RDF graph Set of possible interpretations is reduced monotonically Set of Possible RDF interpretations

45 Interpretations for an RDF graph Possible interpretations