Semantic Web - Group IT v0.4 - draft

8/7/2019 Semantic Web - Group IT v0.4 - draft

http://slidepdf.com/reader/full/semantic-web-group-it-v04-draft 1/14

Group IT

Semantic Web

Krzysztof Kaminski



Information Management

Group IT

Agenda

What is Semantic Web?

Main principles of Semantic Web?

What are the benefits of using Semantic Web Technologies?

How we can use Semantic Web Technologies?

Building Ontology

Questions




Group IT

What is Semantic Web?

³The Semantic Web is an extension of the current web in which information isgiven well-defined meaning, better enabling computers and people to

work in co-oper ation.³

[Berners-Lee et al , 2001]

Semantic Web - is a mesh of information linked up in such a way as to be easilyprocessable by machines, on a global scale.

Semantic web - provides a way of using common language to tag data so that

information exchange can occur in databases and produce an outcome that is

perceptive to the user. It relies on machine-readable information and metadataexpressed in RDF.




Group IT

Main pr inciples of Semantic Web

Explicit Metadata: metadata capture part of the meaning of data. HTML is used

to express meaning of its content in not machine processable way (text). If HTML is replaced by more appropriate languages, then the Web page can

carry their content on its sleeve (currently XML and RDF).

Ontologies: defined as ³an explicit and formal specification of a

conceptualisation³ [R. Studer] are ways of declaring what types of things exist,

and what types of relationships they have with each other. Provide shared

understanding of a domain to use in machine-understandable content.

The ter ms denote important concepts (classes) of domain.

The r elationships typically include hierarchies of classes.

Proper ties i.e. (X surveys Y), (A hasLoad C)

Value r estr ictions (only X can survey B)

Disjointness statement (bulk carrier and oil carrier are disjoint)

Specification of logical r elations between objects (every surveyable

ship must have at least 100 Gross tonnage)




Group IT

Main pr inciples of Semantic Web

Logic : is the discipline that studies principles of reasoning. In general it offers:

Formal languages for expressing knowledge

Well-understood formal semantics

Automated reasoners that can deduct (infer) conclusions from the given

knowledge

Logic can be used to uncover ontological knowledge that is implicitly given. It can

also help to uncover unexpected relationships and inconsistencies (ensure

correctness of model).

Agents: Semantic Web Agents use all technologies we have outlined:

Metadata will be used to identify and extract information from Web sources.

Ontologies will be used to assist in Web searches, to interpret retrievedinformation, and to communicate with other agents.

Logic will be used for processing retrieved information and for drawing

conclusions.




Group IT

What ar e the benef its of using Semantic Web

Technologies?

The main advantages of Semantic Web are:

I nteroperability ± two or more software systems or/and people can function

with each other to achieve common goal.

Knowledge Sharing ± share common structure of information among people

and software agents

I nference

± Usage of reasoner infer relations and inconsistencies (ensurecorrectness of the model)

Disadvantages:

Subscribe for a single predefined meaning of the terms

(cannot be predefined globally)

Require manual mark up of all existing web pages (impossible)




Group IT

What ar e the benef its of using Semantic Web

Technologies?

Semantic Web Enabled Knowledge Management:

Knowledge will be organized in conceptual spaces according to its meaning.

Automated tools for maintenance and knowledge discovery

Semantic query answering

Query answering over several documents

Defining who may view certain parts of information (even parts of documents)will be possible.




Group IT

How we can use Semantic Web Technologies?

Knowledge Base (Rules and Regulations)

Data Integration (Marine Systems)

Knowledge Base (Intranet: The Hub)

Knowledge Base (Marine Domain)




Group IT

Knowledge Base (Rules and Regulations)

Knowledge Base of particular domain:

Effective Search

Machine and human understandable

Evolves at ontology level

Rules and Regulations Knowledge Base:

Serve as a human and machine searchable source of LR Rules and

Regulations

Can be expand over the time to other languages

Versioning capabilities enable storing different releases of Rules and

Regulations throughout the timeline




Group IT

Knowledge Base (The Hub, Mar ine Domain)

The Hub Knowledge Base:

Serve as a human and machine searchable source of The Hub content

Can serve as a glossary of business terms organised in logical hierarchy

Ontology visualisation tools can be used to browse ontology

Marine Domain Knowledge Base:

Serve as a human and machine searchable source of Marine Domain

Can ensure reusability of the same, logically organised objects during

development of enterprise architecture models




Group IT

Mar ine Systems Data Integr ation

General ontology for integration of different data sources and systems

Mappings of concepts

Single queries for multiple systems

Example:

Ship-types rationalised across heterogeneous systems

Note:Oracle 11g has support for RDF and OWL, its own reasoner and

Support for Java API (Jena)



Information ManagementGroup IT

Mar ine Systems Data Integr ation




Building Ontology

Logical Data Model developed during discovery of Ship life-cycle store crucial

information and structure that can be reused, saving substantial amount of effort allocated for development of ontologies.

Ontology development is necessarily an iterative process.

An ontology is a model of reality of the world and the concepts in the ontology

must reflect this reality.

The analytical work is similar to building a conceptual enterprise data model

and involves many of the same skills

One of the interesting differences is that as the ontology is being built it can be

used in connection with data profiling to see whether the information that iscurrently being stored in information systems does in fact comply with the rules

that the ontology would suggest.




Thank you for listening

Any questions?

Semantic Web - Group IT v0.4 - draft

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