Concept Modeling on Semantic Wiki
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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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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)