Using the Semantic Web, and Contributing to it

Using the Semantic Web,and Contributing to it

Mathieu d’Aquin KMi, The Open University – [email protected]

Semantic Web

A large scale, heterogenous collection of formal, machine processable, ontology-based statements (semantic metadata) about web resources and other entities in the world, expressed in a XML-based syntax

<rdf:RDF> <owl:Ontology rdf:about=""> <owl:imports rdf:resource="http://usefulinc.com/ns/doap#"/> </owl:Ontology> <j.1:Organization rdf:ID="KMi"> <rdfs:comment rdf:datatype="http://www.w3.org/2001/XMLSchema#string" >The Knoledge Media Institute of the Open University, Milton Keynes UK</rdfs:comment> </j.1:Organization> <j.1:Document rdf:ID="KMiWebSite"> …

<rdf:RDF> <owl:Ontology rdf:about=""> <owl:imports rdf:resource="http://usefulinc.com/ns/doap#"/> </owl:Ontology> <j.1:Organization rdf:ID="KMi"> <rdfs:comment rdf:datatype="http://www.w3.org/2001/XMLSchema#string" >The Knoledge Media Institute of the Open University, Milton Keynes UK</rdfs:comment> </j.1:Organization> <j.1:Document rdf:ID="KMiWebSite"> … <rdf:RDF>

<channel rdf:about=“http://watson.kmi.open.ac.uk/blog”><title>Elementaries - The Watson Blog</title><link>http://watson.kmi.open.ac.uk:8080/blog/</link><description>"Oh dear! Where the Semantic Web is going to go now?" -- imaginary user 23</description><language>en</language><copyright>Watson team</copyright><lastBuildDate>Thu, 01 Mar 2007 13:49:52 GMT</lastBuildDate><generator>Pebble (http://pebble.sourceforge.net)</generator><docs>http://backend.userland.com/rss</docs>…

<rdf:RDF><channel rdf:about=“http://watson.kmi.open.ac.uk/blog”><title>Elementaries - The Watson Blog</title><link>http://watson.kmi.open.ac.uk:8080/blog/</link><description>"Oh dear! Where the Semantic Web is going to go now?" -- imaginary user 23</description><language>en</language><copyright>Watson team</copyright><lastBuildDate>Thu, 01 Mar 2007 13:49:52 GMT</lastBuildDate><generator>Pebble (http://pebble.sourceforge.net)</generator><docs>http://backend.userland.com/rss</docs>…

Metadata

UoD



<rdf:RDF> <foaf:Image rdf:about='http://static.flickr.com/132/400582453_e1e1f8602c.jpg'> <dc:title>Zen wisteria</dc:title> <dc:description></dc:description> <foaf:page rdf:resource='http://www.flickr.com/photos/xcv/400582453/'/> <foaf:topic rdf:resource='http://www.flickr.com/photos/tags/vittelgarden/'/> <foaf:topic rdf:resource='http://www.flickr.com/photos/tags/wisteria/'/> <dc:creator> <foaf:Person><foaf:name>Mathieu d'Aquin</foaf:name> …

<rdf:RDF> <foaf:Image rdf:about='http://static.flickr.com/132/400582453_e1e1f8602c.jpg'> <dc:title>Zen wisteria</dc:title> <dc:description></dc:description> <foaf:page rdf:resource='http://www.flickr.com/photos/xcv/400582453/'/> <foaf:topic rdf:resource='http://www.flickr.com/photos/tags/vittelgarden/'/> <foaf:topic rdf:resource='http://www.flickr.com/photos/tags/wisteria/'/> <dc:creator> <foaf:Person><foaf:name>Mathieu d'Aquin</foaf:name> …



FOAF

DCRSS TAP

WORDNET

NCI Galen

Music

…… …

…

…

OK, nice… but what’s the reality?

2007 2008 2009

So, Using the Semantic Web?• Many research and development efforts in

– Supporting the design of ontologies (methodologies, toolkits, editors, etc.)

– Supporting the annotation Web resources (natural language processing, information extraction, etc.)

– Supporting the publication of semantic data and information online (linking open data, `semantification’ of legacy information systems

– …

• Resulting in an explosion of the amount of machine processable knowledge online.

• Now the question is: What to do with it? How to exploit it? What are the missing infrastructure components necessary to develop Semantic Web application?

Next Generation Semantic Web Applications

NG SW Application Semantic WebSmart Features

Able to exploit the SW at large

– Dynamically retrieving the relevant semantic resources

– Combining several, heterogeneous Ontologies

Next Generation Semantic Web Applications

Dynamically retrieving, exploiting and combining relevant semantic resources from the SW, at large

Need for a Gateway to the Semantic Web

Watson: a Gateway to the Semantic Web

Architecture

Interface

http://watson.kmi.open.ac.uk

But the important part is: the APIs

• Provide Semantic Web application developers with the ability to efficiently:

– Locate (find) Semantic Web documents online using advanced search functions

– Explore the documents, automatically extracted metadata and content

– Query the documents, to exploit online knowledge in an homogeneous way

• In a set of lightweight APIs, and without having to download the data or use any other dedicated infrastructure.

Some Applications We Developed

Ontology Reuse:The Watson Plugin

Question Answering:PowerAqua

Semantic Browsing:PowerMagpie

Semantic Relation Discovery:Scarlet

Folksonomy Enrichment

And also:Word sense disambiguationQuery ExpansionSynonym Discovery…

Example: The Watson Plugin

Chose an entity to search

Get entities from online ontologies

Integrate statements Into the edited ontology

Example: Scarlet

ka2.rdf

Researcher AcademicStaff

Sem

anti

c W

eb

Researcher

AcademicStaff

⊆

⊆

ISWC SWRCHam SeaFood

Sem

anti

c W

eb

HamSeaFood

Meat

Meat

SeaFood

Agrovoc NALT

⊆

€

⊥

€

⊥

€

⊥

pizza-to-go

wine.owl

NALT

Example: Scarlet

Example: PowerAqua

Natural language question

Answers from online semantic data

Example: FLOR

Can the Semantic Web provide the structure needed to improve search and navigation of tagged spaces?

Search in Tag Spaces

5/24 ≈ 21% relevant

Dog Dog

DogDog

Bird

Bird

Bird

Bird

Bird

Bird

Bird

Tiger

Tiger

Tiger

Tiger

CatLandscape

Landscape

Landscape

Let’s find photos of “animals which live in the water”

Query: Animal Water

Bring in the SW…

Dolphin

Seal

Marine Mammal

Mammal

Sea

livesIn

Whale

Body of Water

Ocean

Sea Elephant

FishlivesIn

Animal

FreshwaterFish

SaltwaterFish

livesIn

Animal Water

<Animal livesIn Water>

<Dolphin>or<Seal>or<“Sea Elephant”>or<Whale>

Results

dolphin

seal

whale

sea elephant

18/24 ≈ 75% relevant

Other Use of Watson/the Semantic Web:Understanding Knowledge Online

Number of entities

Domain covered

Underlying description logic

Other Use of Watson/the Semantic Web:Understanding Knowledge Online

• Looking at relationships between ontologies:

– Inclusion, equivalence: can ontologies being syntactically different, or even represented in different languages represent the same formal model?

– Similarity: How close are two ontologies? How to define similarity between ontologies in particular context?

– Versioning: How to detect if an ontology is a different version from another one? Which on came first? Which is the latest? How to characterize the changes (at syntactic level, at model level)?

– Agreement/Disagreement: How to measure that two ontologies contradict each other? Agree on certain points? Are logical inconsistency/incoherence enough?

• A complete framework based on an ontology formalizing relations between ontologies to detect and reason upon relationships between ontologies in Watson

• Looking at relationships between ontologies:

– Inclusion, equivalence: can ontologies being syntactically different, or even represented in different languages represent the same formal model?

– Similarity: How close are two ontologies? How to define similarity between ontologies in particular context?

– Versioning: How to detect if an ontology is a different version from another one? Which on came first? Which is the latest? How to characterize the changes (at syntactic level, at model level)?

– Agreement/Disagreement: How to measure that two ontologies contradict each other? Agree on certain points? Are logical inconsistency/incoherence enough?

• A complete framework based on an ontology formalizing relations between ontologies to detect and reason upon relationships between ontologies in Watson

Other Use of Watson/the Semantic Web:Agreement/Disagreement in Ontologies

• Ontologies are knowledge artifacts, they express opinions, beliefs

• As such they can differ, contradict each others

• Assessing (dis)agreement in ontologies is very useful to understand how to combine knowledge from different sources

• A possible approach would be to check whether inconsistencies and incoherencies appear while combining the ontologies. However we believe that:

– There are di erent levels of agreement/disagreement ff

– Covering di erent domains is not agreeing ff

– It is possible to agree and disagree at the same time

• Based on these requirements we define a set of measures for assessing (dis)agreement between statements and ontologies.


• Agreement(st, O) [0..1] and Disagreement(st, O) [0..1] where st is a statement <subject, predicate, object> and O is an ontology

• Based on extracting the part of the ontology that express a relation between subject and object

• (Dis)agreement between ontologies:

• Global (dis)agreement in a repository

• Consensus:

• Controversy:


• Experiment: assessing statements related to the class Seafood in Watson:

a: global agreement, d: global disagreement, cs: consensus, ct: controversy

• More experiments on the Way!

Contributing to the Semantic Web

• So, using the Semantic Web is all about exploiting what is made available online, as distributed, heterogeneous knowledge in ontologies

• Our ability to do that therefore depends on the availability of ontologies, semantic information and machine processable data.

• More precisely on the availability of quality knowledge on the Semantic Web

• And incidentally on the availability of quality information about ontologies

Slide 27

From a Semantic Web search engine…

Slide 28

… to Ontology Repositories?

Ontologies

Ontology Metadata

Versions of

Alignments

Comments and

Reviews

Cupboard

Using the User?

• How ontologies are used and reused in applications and other ontologies can also provide interesting information about these ontologies, i.e. contributions in the form of quality information

• We develop a trust engine which can collect positive or negative evaluations for ontology statements, from various users and applications, to propagate this information for ranking ontology entities.

• Application to the Watson plugin.

Automatic evaluation of statements through a trust engine

Watson Trust Service

Trust Propagation

YouClick Here

This statementis goodRanking for

statements/entities

Example - Evaluation as a Side Effect

Example - Ranking According to Trust

Example - Propagation

Final message

• I hope I convinced you that

Using the Semantic Web Contributing to the Semantic Web

• Through Watson, Cupboard and our applications, our aim is to build an open and efficient platform making the Semantic Web a `playground for research and development’

• There is still a lot to do, and everybody is welcome to comment, help, contribute…

Thank You!

Mathieu d’Aquin ([email protected], http://people.kmi.open.ac.uk/mathieu) With contributions from many people in Kmi (http://kmi.open.ac.uk) and the NeOn project (http://neon-project.org)

/* I would normally include a bibliography slide at the end, but all the relevant papers can be found on these 3 websites */

mailto:[email protected]

http://people.kmi.open.ac.uk/mathieu

http://kmi.open.ac.uk/

http://neon-project.org/

Using the Semantic Web, and Contributing to it

Technology

semantic web documents

semantic web alargescale

use of watsonthe semantic

relevant semantic resources

publication of semantic

online ontologies

poweraqua semantic browsing

heterogeneous ontologies