The document discusses the evolution of the web from Web 1.0 to Web 2.0 and the problems with representing meaning. It introduces semantic web as representing things rather than just documents using semantic annotations in formats like RDFa, microformats and microdata. Linked data allows complex queries across a web of data by embedding semantic annotations and using common schemas like Schema.org. Major companies are now building knowledge graphs to represent structured data from sources on a linked open web.
Strategize a Smooth Tenant-to-tenant Migration and Copilot Takeoff
Semantic Linked Data
1. Semantic Linked Data
Kouroupetroglou Praxitelis Nikolaos
Postgraduate Student
Department of Computer Science
Aristotle University, Thessaloniki, Greece
Master Studies – Web Data Mining
Instructor: Vakali Athena
2. What is about? – Origins?
Web 1.0
◦ The Internet is a huge network of
computers that uses TCP/IP to
communicate, Lot of documents
interlinked via the internet
◦ Users have a passive role, they just
receive a page
Web 2.0
◦ People started to interact with pages,
forums, social networks, blogs etc.
Problem
◦ Web Pages are written in HTML,
describing the structure and not the
3. Tackle the Problem
Semantic Web is about Things instead of
today’s Web is about Documents
Solutions
◦ Top Down
◊ Need: Information Analysis, Web scraping,
natural language processing
- Expensive! Human Intervention, hard to
maintain, legal issues
◦ Bottom Up
◊ Embedding sematic annotations into the web
pages
5. Semantic Annotations
RDFa, W3C
◦ Foaf, Doap, Dublin Core, Review Vocabulary,
Music Ontology, GoodRelations etc
Microformats
◦ hReview, hCalendar, hCard, etc
Microdata
◦ Is a HTML specification, used to nest metadata on
web pages
So many standards, solution: Schema.org
◦ Created by Bing, Google and Yahoo in June 2011
◦ support a common set of schemas
◦ Inspired by other formats
6. Linked Data Arrival
Almost every major Web company has now announced
their work on a knowledge graph
Dbpedia example
◦ open-source knowledge graph since 2006.
◦ Extract structured information from Wikipedia and make it
available on the Web.
Linked Data
◦ Web 2.0 technologies allowed websites to be re-used from
third-parties and to repurpose data on the Web, a road to Web
3.0
Linked Data benefits
◦ can navigate in Web of Data, complex search queries
7. Summary
“I have a dream for the Web in
which computers become
capable of analyzing all the
data on the Web”
Tim Berners Lee, 1999, Invertor of the Web
8. Semantic Linked Data
Kouroupetroglou Praxitelis Nikolaos
Sources:
• www.w3.org
• semanticweb.org
• linkeddatatools.com
• microformats.org
• microdata wikipedia
• semantic-web-and-linked-data presentation
• tutorial-on-semantic-web-presentation
Thank you for listening
Hinweis der Redaktion
A lot of information given without semantics, just interlinked web pages
Unicode
How characters are represented
URI
Addressing docs / objects across the web
XML layer
Metadata
Syntactic basis (send docs across the Web)
RDF layer
Metadata – semantic layer
RDF basic data model for facts
Does not rely on XML, but has XML-based syntax
RDF Schema simple ontology language (metadata vocabulary)
Ontology layer
More expressive languages than RDF Schema
Current Web standard: OWL
Logic layer
enhance ontology languages further
application-specific declarative knowledge
Proof layer
Proof generation, exchange, validation
Trust layer
Digital signatures
recommendations, rating agencies ….
Annotation: tag semantically your web site
Commonly used Vocabularies
Friend-of-a-Friend (FOAF) provides terms for describing people and their social network
DOAP Description of a Project
Dublin Core Defines general metadata attributes.
Review Vocabulary provides terms for representing reviews.
GoodRelations provides terms for describing products and business entities.
Music Ontology provides terms for describing artists, albums, tracks, but also performances, arrangements, etc.
Microformats
Designed for humans first and machines second, microformats are a set of simple, open data formats built upon existing and widely adopted standards. Based on XML
Microdata
Provides tag and tag attributes for semantic annotation, Search engines benefit greatly from direct access to this structured data because it allows search engines to understand the information on web pages and provide more relevant results to users.
The Knowledge Graph is a knowledge base used by Google to enhance its search engine's search results with semantic-search information gathered from a wide variety of sources. Knowledge Graph display was added to Google's search engine
Google Knowledge Graph
Yahoo! Web of Objects
Walmart Lab Social Genome
Microsoft Satori Graph / Bing Snapshots
Facebook Entity Graph
Semantic Queries: Cities with low criminality, the next Elton John