Date post: | 12-Aug-2015 |
Category: |
Software |
Upload: | valentin-sviridov |
View: | 137 times |
Download: | 0 times |
Semantic Wikis
Valentin Sviridov
13/12/2013 COMASIC M2 2013 - Web Sémantique 1
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
13/12/2013 COMASIC M2 2013 - Web Sémantique 2
Why bother?
• Traditional Wiki problems
– Data coherency
– Data access
– External data usage
– Tags/categories hell
• Export to RDF
13/12/2013 COMASIC M2 2013 - Web Sémantique 3
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
13/12/2013 COMASIC M2 2013 - Web Sémantique 4
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
13/12/2013 COMASIC M2 2013 - Web Sémantique 5
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
13/12/2013 COMASIC M2 2013 - Web Sémantique 9
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
13/12/2013 COMASIC M2 2013 - Web Sémantique 10
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
13/12/2013 COMASIC M2 2013 - Web Sémantique 11
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
13/12/2013 COMASIC M2 2013 - Web Sémantique 12
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
13/12/2013 COMASIC M2 2013 - Web Sémantique 13
Wild nature Semantic Wikis • Public wikis
• Internal usage
13/12/2013 COMASIC M2 2013 - Web Sémantique 14
Semantic Wiki engines
• Semantic MediaWiki
– Semantic Forms
– Semantic Result Formats
– Semantic Maps
• Ontowiki
13/12/2013 COMASIC M2 2013 - Web Sémantique 15
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]]
13/12/2013 COMASIC M2 2013 - Web Sémantique 16
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.
13/12/2013 COMASIC M2 2013 - Web Sémantique 17
OWL Conversion
• OWL/RDF
– Wiki Page = OWL abstract entity
– Property = OWL property
– Category = OWL class
13/12/2013 COMASIC M2 2013 - Web Sémantique 18
Example
13/12/2013 COMASIC M2 2013 - Web Sémantique 19
Text written with MediaWiki
Text written with Semantic MediaWiki
Querying
– Query results and output as part of the wiki text
– #ask function
13/12/2013 COMASIC M2 2013 - Web Sémantique 20
Query Condition
Output Values
{{#ask: [[Category:City]] [[located in::Germany]] | ?population | ?area#km² = Size in km² }}
What can you do?
• Research
– Data extraction techniques
– Ontologies
• Pass a message
13/12/2013 COMASIC M2 2013 - Web Sémantique 22
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
13/12/2013 COMASIC M2 2013 - Web Sémantique 23