Towards Linked Ontologies and Data on the Semantic Web

Towards Linked Ontologies and Data on the Semantic Web Jie Bao , Rensselaer Polytechnic Institute baojie@cs.rpi.edu, http://www.cs.rpi.edu/~baojie Oct 1st, 2009

Outline
Personal Background & Research Overview
Linked Ontologies: a modular ontology approach
Linked Data: a semantic wiki based approach
Ongoing/Future Work

Personal Background

Research Overview /48

Research Overview They are all about the power of linking…

Research Overview Linked Ontologies Linked Data

Part I
Linked Ontologies

Roadmap Semantic Web

Why not owl:imports? owl:imports

Why not owl:imports? owl:imports (Alice, 2001) (Bob, 2009) Analogy: Paper Writing in the OWL fashion Recent development in Web… In this paper, we extend the algorithm A proposed by (Alice,2001) … Recent development in algorithms … In this paper, we present two algorithms A and B to …

Why not owl:imports? (Bob, 2009) Analogy: Paper Writing in the OWL fashion In this paper, we extend the algorithm A proposed by In this paper, we present two algorithms A and B to … Recent development in algorithms … Recent development in Web…

P-DL: Importing akin to Citation P-DL imports (Alice, 2001) (Bob, 2009) Paper(Bob2009) {Bob2009} ⊑  propose.{AlgC} {AlgC} ⊑  extend.{ AlgA } {Bob2009} ⊑  cite.RecentDev Paper(Alice2001) {Alice2001} ⊑  propose.{ AlgA } {Alice2001} ⊑  propose.{AlgB} {Alice2001} ⊑  cite.RecentDev [ISWC 2006; ASWC 2006; AAAI 2007, AAAI 2008] P-DL = Package-based Description Logics

P-DL: Semantics People Animals O 1 O 2 Only “relevant” local domains are connected Expressions are interpreted in local domains (e.g., neg)

Modular ontology languages: Comparison Distributed DL E-Connection P-DL What can you import? Nothing Concept name, Nominal name Concept , Role, and Nominal name What can you do with the imported names syntactically? (bridge rules between concepts and between roles) Use it in the range of a (link) role Free use, except that imported roles can not be used in role inclusions What is the result semantically? Decidability with BR between concepts. Decidability Decidability , Transitive Reusability, Preservation of Unsatisfiability

Reasoning with P-DL
Major Considerations
[WI 2006]

P-DL Federated Reasoning Dog Dog ⊑ Animal P 2 P 1 What is a “Dog”? “ Dog” is a type of “Animal”

P-DL Federated Reasoning messages

Privacy Matters
A reasoner may pose queries to another reasoner (of a remote ontology)
However, not everything is public.
[WI 2007]

Private Knowledge Locally visible : Has date Q: Has date? A : Unknown Bob’ schedule ontology Q: Busy? A : Yes Q: Has dinner? A : Unknown indistinguishable

Privacy-Preserving Reasoners More informative More general Dummy Reasoner “ Combina-tion Safe” Reasoner Naive Reasoner Gives information Always answer “U” ? Always answer faithfully Safety scope All ontologies Ontologies that have no hidden knowledge

Privacy-Preserving Reasoners
Reasoner I: iff a statement is hidden, answer “unknown”.
Reasoner II: iff a statement may be used in inferring a hidden statement, answer “unknown”.
Reasoner III: it will NOT give more knowledge (except the public knowledge) about the signature of the hidden KB.
Using the notion of “Locality” in DL.
(See [WI 2007] for formal definitions) More informative More general

Part II
Linked Data
- A semantic wiki based approach

Why Semantic Wiki
Linked data ready
Support both structured and unstructured data.
Simple syntax, Low learning curve
Inherent collaboration support
Browser-based, Cross-platform
Semantic Wiki

Example: Semantic History
Turn wiki revision history into semantic data
Demo site: http://tw.rpi.edu/semhis

Semantic History (v1)
Expose history in
RDF using PML
Query data and its
provenance metadata
http://tw.rpi.edu/Help:SemanticHistory RDF/XML data displayed in Tabulator

Semantic History (v2) [SDOW 2009]

{{ SH_Triple |…}}
{{ SH_Add |…}}
{{ SH_Delete |…}}
User makes edits SMW The Semantic History (SH) extension captures edit actions SH Templates (customizable) Revision history SH Templates generates semantic descriptions of revision history Triple Representation of history User Triplified revision history are added to and managed by the SMW Applications use the triplified revision history for various purposes /48

Semantic History: Example (Provenance tracking) Who has changed the first name of James Hendler? http://tw.rpi.edu/proj/semhis.wiki/index.php/Example_4

Semantic History (v2): Example (Statistics and Visualization)

Other Data Generation Services A few other SMW extensions I have worked on:

Concept Modeling Person Name Role Alias Affiliation Project Name Member Issue ID Project Assignee Jim Hendler Professor hasRole Person rdfs:subClassOf Alice John hasUncle Alice Bob John isParentOf isBrotherOf RDF Modeling Relational Modeling Rule Modeling

Rules: Logic Programs RightHanded(x):-Person(x), not LeftHanded(x). {{LP Rule |body= 1::Person; 1:not:LeftHanded |head= RightHanded }} Example : every person is by default right-handed, unless that person is known to be left-handed: See details at: http://tw.rpi.edu/proj/cnl/Template:LP_Rule [ACITA 2009]

Rules: Integrity constraints
IC describes errors in a dataset
Example : notOK :- Person(x), not HasGender (x,y) See details at: http://tw.rpi.edu/dev/cnl/Integrity_Constraint

Semantic Wiki: Application Workbench [ASWC 2009]

Case Study: CNL Wiki
A Wiki-based ontology editor
Supports ontology representation in Controlled Natural Languages (CNL).
http:// tw.rpi.edu/proj/cnl [CNL 2009]

Case Study: CNL Wiki Class(Rabbit partial intersectionOf(animal restriction(eat someValuesFrom(FreshVegetable))) OWL: “Rabbit is Animal and eats some fresh vegetable” Us wiki templates to create OWL meta-model extensions for SMW Form-based editing interface associated with templates

Case Study: CNL Wiki

Case Study: RPI Map /48

Ongoing/Future Work

Some Other Recent Research Activities
TAMI & AIR (2009)
Policy testbed and AIR formulation(With Li Ding and Ankesh Khandelwal)
OWL Working Group (2008-2009)
Authored rdf:plainLiteral and OWL Quick Reference Guide
Integrity Constraint and Closed World Reasoning (2008-2009)
IC language for Semantic Web(with Jiao Tao)
INDUS (2003-2006)
Semantic data integration in the bioinformatics domain

Some Ongoing/Planned Work
Linked Data
Turn government data into wiki data /RDF
Semantic search with RDFa / SMW
Policy and Trust
Privacy-preserving query with SMW
Information accountability and access control in SMW
Trust computation based on semantic history
Web-scale Computing
Scalable “is-a” reasoner
OWL-RL reasoner

Long-term Goal Email Picture Phone Call Shopping music video Web Server Farm

Conclusion
“ A little semantics goes a long way”
a.k.a. Hendler Hypothesis

Acknowledgements
Work at ISU: Vasant Honavar (Ph.D. advisor), Giora Slutzki, George Voutsadakis, Doina Caragea
Work at RPI: James Hendler (supervisor), Deborah L. McGuinness, Peter Fox, Li Ding, Zhenning Shangguan, Rui Huang, Jin Guang Zheng, Ankesh Khandelwal
Funding support from NSF, NIH, USDA, Army Research Laboratory and DARPA.

References (modular ontologies)
Bao, J., Voutsadakis, G., Slutzki, G. Honavar, V. Package based Description Logics. Book Chapter in Ontology Modularization, pages 349-371. Berlin: Springer, 2009
Bao, J., Voutsadakis. G., Slutzki, G. and Honavar, V. On the Decidability of Role Mappings Between Modular Ontologies. In AAAI 2008, pages 400-405.
Bao, J., Slutzki, G., and Honavar, V. Privacy-Preserving Reasoning on the Semantic Web . In Web Intelligence 2007. ( Slides) pages 791-797.
Bao, J., Slutzki, G., and Honavar, V. A Semantic Importing Approach to Knowledge Reuse from Multiple Ontologies . In AAAI 2007, pages 1304-1309.
Bao. J., Caragea, D., and Honavar, V. A Tableau-based Federated Reasoning Algorithm for Modular Ontologies , In Web Intelligence 2006, pages 404-410.
Bao. J., Caragea, D., and Honavar, V. On the Semantics of Linking and Importing in Modular Ontologies . In International Semantic Web Conference 2006, LNCS 4273, pages 72-86.
Bao. J., Caragea, D., and Honavar, V. Modular Ontologies - A Formal Investigation of Semantics and Expressivity . In Asian Semantic Web Conference 2006, LNCS 4185, pp. 616-631.
http://tw.rpi.edu/wiki/Jie_Bao_Publication

References (semantic wikis)
Bao, J. Ding, L., Huang, R., Smart, R., Braines, D., Jones, G. A Semantic Wiki based Light-Weight Web Application Model, In Proceedings of the 4th Asian Semantic Web Conference, pp. In Press, 2009 .
Bao, J., Ding, L., & McGuinness, D.L. Semantic History: Towards Modeling and Publishing Changes of Online Semantic Data, In The 2nd Social Data on the Web workshop (SDoW2009), In Process.
Bao, J., Ding, L., Smart, R., Braines, D., & Jones, G. Rule Modeling using Semantic MediaWiki, In 2nd Annual Conference of the International Technology Alliance, pp. In Process, 2009
Bao, J., Smart, P., Braines, D., & Shadbolt, N. A Controlled Natural Language Interface for Semantic Media Wiki Using the Rabbit Language. In Workshop on Controlled Natural Language (CNL) 2009.
Bao, J. and Hendler, J., Ding., L. Knowledge representation and query in semantic mediawiki: A formal study. In Tetherless World Constellation (RPI) Technical Report, No TW-2008-42, http://tw.rpi.edu/wiki/TW-2008-42, 2008.
Bao, J., Ding, L., McGuinness, D., Hendler, J. Towards Social Webtops Using Semantic Wiki, In International Semantic Web Conference (ISWC), Poster Track, 2008
/48 http://tw.rpi.edu/wiki/Jie_Bao_Publication

Backup

P-DL: Additional Properties Dog Dog⊑ Animal Pet Animal O 1 O 2 O 3 ⊑ ⊑

P-DL Federated Reasoning Bob2009 Alice2001 cite

Privacy-Preserving Reasoning
Protect hidden knowledge as if it is incomplete knowledge
Both are answered “unknown”
But when to answer “unknown”?
People may combine “safe” answers to infer hidden knowledge

Privacy-Preserving Reasoning Queries Yes Unknown

Semantic MediaWiki (SMW)
It is the most popular semantic wiki system extending MediaWiki
Mediawiki: What you edit what you see

Semantic MediaWiki SMW: What you edit (Modeling Script) what you see To author knowledge typed link (property)

Semantic MediaWiki SMW: What you edit (Querying Script) what you see To retrieve knowledge

SMW Semantics and Complexity (Theory) See proofs in [TW-2008-42] Recall that L  NL  P  NP SMW RDF Modeling Language Translatable into positive logic programs NL-complete
NP-complete;
P-complete for grounded graph [Bruijn and Heymans 2007]
Query language
Translatable into positive logic programs
P-complete;
In L without subqueries
(SPARQL) P-complete [Perez et al 2006]

Formalize SMW Query (Theory)
{{#ask: [[Category:A]][[p3::category:B]] or
[[ p.p1.p2 ::
<q>[[Category:D]] or [[p1::<q>[[SomePage]]</q>]]</q> || !v || <q>[[Category:E]]</q>
]]
}}
_result(x) :- _tmp0(x).
_tmp0(x) :- A(x), p3(x,x0), x0=category:B .
_tmp0(x) :- p(x,x2), p1(x2,x3), p2(x3,x1), _tmp9(x1).
_tmp9(x1) :- _tmp12(x1).
_tmp12(x1) :- D(x1).
_tmp12(x1) :- p1(x1,x4), x4=SomePage.
_tmp9(x1) :- x1!=v.
_tmp9(x1) :- E(x1).

Case Study: RPI Map

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Towards Linked Ontologies and Data on the Semantic Web

by Jie Bao on Oct 06, 2009

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