concept modeling on semantic wiki

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Concept Modeling on Semantic Wiki Presented by Jie Bao, RPI [email protected] http://baojie.org Joint work with Li Ding and Zhenning Shuangguan Nov 22, 2008 1

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Concept Modeling on Semantic Wiki. Presented by Jie Bao, RPI [email protected] http://baojie.org Joint work with Li Ding and Zhenning Shuangguan Nov 22, 2008. SMW and me. For research TW group portal wiki-master - PowerPoint PPT Presentation

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Page 1: Concept Modeling on Semantic Wiki

Concept Modeling on Semantic Wiki

Presented by Jie Bao, [email protected]://baojie.org

Joint work with Li Ding and Zhenning Shuangguan

Nov 22, 2008

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Page 2: Concept Modeling on Semantic Wiki

SMW and me

• For research– TW group portal wiki-master– Testbed for ideas: semantic history, privacy-preserving

reasoning, integrity constraint, close world reasoning

• For fun and daily life– Blog– Time management (To-do list, issue tracker, calender)– Document everything (emails, papers, drafts,…)

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Outline

• 1. A formalization of SMW– The modeling language (SMW-ML)– The query language (SMW-QL)

• 2. Template-based Rule Modeling

• 3. OWL Meta Modeling (will be presented by Zhenning Shuangguan)

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1. Formalization of SMW

Why it matters? It• Gives a better understanding on SMW’s

– potentials (what it can do) and – limitations (what it can not do)

• Allows evaluation of implementation, e.g., soundness and completeness

• Promotes community-wide adoption, e.g., on multiple DB platforms.

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Modeling language (SMW-ML)

• Syntax

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Modeling language (SMW-ML)

• Semantics: a variation of the RDF semantics– Resources can only be local wiki pages– N-ary property supported– No domain, range, blank node, collection and list– Classes and properties are disjoint– Allow punning between classes and individuals

• Details in [Bao & Ding, 2008]

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Modeling language (SMW-ML)

• Entailment rules (sound and complete)

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Query Language (SMW-QL)

• Syntax in BNF

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Query Language (SMW-QL)

• Some observations– Subquery can allow “punning” of class & ind., e.g.,

• [[Has topic::<q>[[Category:Wiki]]</q>]]• [[Has topic::Category:Wiki]]

– Selection: • top level is in Conjunctive Normal Form (CNF), e.g., (A

and B) or (C and D)

– “Concept” pages:• Are wiki “views” – may be tricky, e.g., concept

containment, or cyclic definition.

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Query Language (SMW-QL)

• Semantics: by translating into logic programs (LP)– E.g., Husband(x) :- Man(x), marriesTo(x,y)

• Why doing so?– Have a precise understanding of what a query means– Formal foundation for query answering, e.g., will the

answer set always be unique?– Better position for future extensions, e.g., adding classical

negation and negation-as-failure.

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Query Language (SMW-QL)

• Semantics: by translating into logic programs (LP)– Minimal Herbrand model semantics– Closed world assumption (why?)– Details in [Bao & Ding, 2008]

• Example

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{{#ask: [[Category:Graduate Student]] [[Has affiliation::RPI]] |?Hobby}}

Q(x,y) :- L(x), Hobby(x,y);L(x) :- A1(x), A2(x);A1(x) :- Graduate Student(x);A2(x) :- Has affliation(x,RPI);

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2. Rule Modeling

• Example: Template-based “Domain” inference

{{#vardefine:value|{{#ask:[[:{{FULLPAGENAME}}]]|?{{{1}}}=|mainlabel=-|format=list|link=none}} }}

{{#if:{{#var:value}}|[[Category:{{{2}}}]]}}

Usage: {{Rule:Domain|hasAuthor|Document}}

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“Rule:Entailment”

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2. Rule Modeling: Example

http://tw.rpi.edu/wiki/Family_Rule

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2. Rule Modeling

• Simplicity – rule as page, easy to design, easy to use• Scalability

– Each page can selectively turn on/off rule inference– Do not enforce completeness (which does not always

matter on wiki)

• Flexibility– Client-sided controllable – Highly extensible (rules can be added on the fly)

• Expressivity: way beyond OWL.– Yet always terminates (due to incompleteness)

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Ongoing work

• Design Patterns on SMW: relational modeling, OO-modeling, advanced rule modeling– Help to bridge the gap between non-SW developer

and SW technologies, – On-the-fly, client side expressivity extensions to basic

semantic wikis, e.g., OWL-RL/SWRL/RIF support

• Ontology Meta Modeling on SMW– OWL and OWL 2– First Order Logic

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Questions?

Reference• Jie Bao and Li Ding (2008) Knowledge Representation and

Query in Semantic Wikis: A Formal Study. Tetherless World Constellation Technical Report. http://www.cs.rpi.edu/~baojie/x/smw-bao-tr.pdf

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Backup

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Query Language (SMW-QL)

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Semantics: by translating into logic programs (LP)