Project partner Panos Mitzias (CERTH/ITI) introduces the importance of semantic web and ontologies in the context of PERICLES research topics.

1. GRANT AGREEMENT: 601138 | SCHEME FP7 ICT 2011.4.3
Promoting and Enhancing Reuse of Information throughout the Content Lifecycle taking account of Evolving Semantics [Digital
Preservation]
Semantic Web & Ontologies
Panos Mitzias (CERTH/ITI)

2. ◦The case: Global information cannot be utilized efficiently.
We need to search, select, read/listen/watch, combine, use,
create, publish vast amounts of information.
◦The problem: Computers do not understand meaning!
◦The Semantic Web vision:
“The idea of having data on the web defined and linked in a way
that it can be used by machines not just for display purposes,
but for automation, integration and reuse of data across
various applications.”
[www.w3.org/ECommerce]
The Semantic Web

3. "The Semantic Web is an
extension of the current web
in which information is given
well-defined meaning, better
enabling computers & people
to work in cooperation."
[Tim Berners-Lee]
The Semantic Web
https://en.wikipedia.org/wiki/Semantic_Web_Stack

4. By enabling/facilitating:
◦the expression of data and their meaning
metadata
standards (for universal approach)
◦the simpler, automatic processing of data
◦broader connections between similar sources of data
◦enhanced reasoning
◦better access, searching, etc.
How does Semantic Web help?

5. “... a formal, explicit specification of a shared conceptualization...”
[Studer et al., 1998]
◦Upper-level ontology: A model of the common objects that
are generally applicable across multiple knowledge domains.
◦Domain ontology: A model of concepts that belong to a
specific domain or part of the world.
What is an Ontology?
machine readable
with computational
semantics
unambiguous concepts,
properties, functions,
axioms definition
commonly
accepted
consensual
knowledge
abstract, simplified
model of a domain
[Studer et al., 1998] Studer, R., Benjamins, V.R. and Fensel, D. (1998), Knowledge engineering: Principles and methods.
Data & Knowledge Engineering, Elsevier Ltd, Vol. 25, Issues 1-2, pp. 161-197

6. ◦Classes (concepts)
Superclass/subclass relationship
◦Properties (relationships)
Subject → Predicate → Object
◦Axioms, restrictions and constraints
◦Individuals (instances)
OWL - the Web Ontology Language
Key Notions

7. ◦Analysis and formalization of the domain knowledge.
◦Semantic representation/interpretation of information.
◦Sharing common understanding of the structure of
information.
◦Reuse of domain knowledge.
◦Reasoning to infer new information.
◦Ensure consistency of the domain representation.
Why are Ontologies Useful?

8. Pros:
◦Variety of existing tools for representation, consistency
checking, reasoning, risk assessment etc.
◦Great fit for model-driven DP → queries & rules.
Cons:
◦Not fully mature technology yet.
◦Significant expertise and effort needed.
Why PERICLES likes Ontologies?

9. Thank you!