Semantic wikis

Semantic Wikis

Valentin Sviridov

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Some parts are taken from “Semantic Wikipedia” presentation by Aaron Gallant and Sung Kim

Plan

• Introduction – Why bother? – What is Semantic Wiki? – History and people behind

• Practical point of view – How does it work? – How is it used?

• Conclusion – How to take part? – Q&A

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Why bother?

• Traditional Wiki problems

– Data coherency

– Data access

– External data usage

– Tags/categories hell

• Export to RDF

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What is Semantic Wiki?

• Model of knowledge

– Machine processing is possible

• Regular Wiki

– Structured text and untyped hyperlinks

• Semantic Wiki

– Identifiable information with typed hyperlinks

– Metadata

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MediaWiki Structures

• Wiki Text: Markup language – Relation between entities

• Hyperlinks : Redirect to different pages – [[PAGE_NAME]]

• Category: classify pages and gives structures – [[Category: CATEGORY_NAME]]

• Synonymous – Redirect mechanism

• Homonymous – Disambiguation page

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MediaWiki Structures

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Category

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Semantics: Shaken, not Stirred

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Typical features and examples

• Features – Relate data (X is author of Y) – Assign attributes to pages – Search and filter (list of books published in French in

1965) – Automatic updates of dependent pages

• Usage examples – Bibliography – Genealogy – Catalogues – Biology-related databases

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History

• 2001 – Wikipedia launched

• 2003 – Mention of Semantic Wiki

– L. Sauermann. The Gnowsis – Using Semantic Web Technologies to build a Semantic Desktop. Master’s thesis, Vienna University of Technology, 2003.

• Middle of 2000s – PlatypusWiki (2004); Rhizome (2005); IkeWiki (2006); OntoWiki (2006)

• Today

– Semantic MediaWiki is the most widely used

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People • Tim Berners-Lee

– Web creator – Coined Semantic Web term

• Jimmy Wales and Larry Sanger – Wikipedia project

• Markus Krötzsch, Denny Vrandečić and Max Völkel – Semantic MediaWiki in 2005

• Agile Knowledge Engineering and Semantic Web (AKSW) research group, University of Leipzig – DBpedia and OntoWiki

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How does it work?

• Semantics included or placed separately

• Syntax: Wiki, OWL, RDF

• Ontologies: internal or “standard” ones

• Some wikis provide querying and reasoning support

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How is it used?

• Show similar articles

• Derived information

– Place in the hierarchy

• Browse link types: show all capitals

• Semantic search

– SPARQL

– Usual search + refinement

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Wild nature Semantic Wikis • Public wikis

• Internal usage

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Semantic Wiki engines

• Semantic MediaWiki

– Semantic Forms

– Semantic Result Formats

– Semantic Maps

• Ontowiki

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Semantic MediaWiki

• Extension to MediaWiki: special annotations • Features

– Automatically-generated lists – Visual display of information (maps, graphs, …) – More simple data structure (no “1620s births” any more) – Searching – External use: CVS, JSON, SPARQL, RDF

• Syntax: [[Property name: Value]] – Hyperlinks

• E.g. London [[capital of: England]]

– Data value • E.g. London [[Population: 7,421,328]]

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Properties

• Predefined Properties

• Custom Properties – Declare Properties

• Property Namespace – E.g. Property: Population

• Define property’s type with has type: attribute – Possible data types: “String”, “Date”, “Geographic Coordinate”,

“URL”

– E.g. Population [[has type: Number]]

• Units Definition, Value validation, Property Hierarchy, etc.

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OWL Conversion

• OWL/RDF

– Wiki Page = OWL abstract entity

– Property = OWL property

– Category = OWL class

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Example

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Text written with MediaWiki

Text written with Semantic MediaWiki

Querying

– Query results and output as part of the wiki text

– #ask function

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Query Condition

Output Values

{{#ask: [[Category:City]] [[located in::Germany]] | ?population | ?area#km² = Size in km² }}

Export

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What can you do?

• Research

– Data extraction techniques

– Ontologies

• Pass a message

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Web 3.0?

• People keep asking what Web 3.0 is. I think maybe when you've got an overlay of scalable vector graphics – everything rippling and folding and looking misty – on Web 2.0 and access to a semantic Web integrated across a huge space of data, you'll have access to an unbelievable data resource ...

Tim Berners-Lee, 2006

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Questions?

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