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Posts Tagged ‘OWL’

OWL : Ontology example

Posted by Aditya Thatte on November 11, 2008

Ontologies describe the relationships between entities on a conceptual level. It shows the hierarchy of classes and subclasses for an object-entity , for eg ( computer ).It decribes subclass relationships , disjointness , constraints , information between objects. It provides vital information to search agents , intelligent agents , databases.
Agents use ontologies and perform powerful reasoning to represent knowledge. Ontologies are modelled using Web Ontology Language ( OWL ). OWL has different flavors varying inexpressiveness of web content.

OWL Full – Highly expressive , but no computational guarantee
OWL DL – Less expressive than OWL-Full , but efficient reasoning provided
OWL Lite – Least expressive , high reasoning support

Lets have a look at an example

geography_ontology

Above figure illustrates an ontology for a country , show subclass relationships , the “parent” class being “country” . The classes lower in the hierarchy represent the “subclassof ” relationship.

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The Semantic Web : An Introduction

Posted by Aditya Thatte on November 11, 2008

The Semantic Web is an initiative aimed to build an intelligent architecture for the web. Today’s web is identified by markup languages like HTML  , XML , which is  ofcourse syntax based and understood by browsers. The browser agent understands the syntax and renders the page accordingly , but does not understand the meaning of the elements and its relationships with other elements used in the document.

For example , the statement ” Aditya Thatte works in TIBCO Software ” is interpreted by the current infrastructure as a pure HTML paragraph , <p> Aditya Thatte works in TIBCO Software</p>

The above sentence can be understood by humans but not by computers.The Semantic Web enables computers to understand data that describes data ( metadata ).
 The aim is to create web content machine-interpretable , so that software agents can access data ( resources ) from disparate sources and link data. The idea is to use existing knowledge to create new knowledge.

In contrast to the above interpretation ,  the semantic web can enable computers understand the above statement as ” Aditya Thatte “works” in TIBCO Software ” i.e the relationship between Aditya Thatte and TIBCO Software , which apparently is “works ” or in other words ” is an employee of ” .

All the above said and done , the Semantic web uses AI , logic , powerful reasoning mechanisms ,inference engines, and markup languages like Resource Description Framework (RDF) , Web Ontology Language (OWL) to create an intelligent architecture.

RDF is a standard which describes resources ( information ) on the web. OWL aims at representing related concepts using ontologies. The semantic web has various applications like semantic search , semantic Web services ( SWS ) , bioinformatics etc.
Here we shall look at how we can use the power of semantic web technologies and apply it to web services to automate the processes of discovery , invocation , composition and mediation.

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