Represtation formalism-ONTOLOGIES
Represtation formalism-ONTOLOGIES
Introduction;
Ontologies can be viewed a representation ormalism.Ontologies are special kinds of knowledge,resourses ranging from simple taxoonomies like hierarchies of domains available in search engines such as altavista and google and hieracy of topics for biological cateogorization,to complex ontologies embedded in formal systems with reasoning capabilities allowing for new knowledge to be deducted from exixting,automatic classification via consistency checks
Definition;
It is defined as a science of study or being;specially , a branch of metaphysics relating to the nature and relations of being;a particular system according to which problems of the nature of being investigated
It is also defined as a theory concerning the kind of entities and specially the kinds of abstract entities that are to be admitted to a language system.''used in computer science and knowledge engineering
Diffent interpretation of Ontologies:
Gurino and Gieraretta[1995] in thier paper''ontology and knowledge bases''state seven different interpretationfor the term ontology
1.Ontology as a physiological discipline
2.Ontology as a informal conceptional system
3.Ontology as formal sementic account
4.Ontology as arepresentation of a conceptional system via a logical theory
5.Omtology as a specifiacation of conceptualization
6.Ontology as a vocuabulary used by logical theory
7.Ontology as a metalevel specification of logical theory
Gruber defines Ontology as an explicit specification of a conceptualization.thus classification of ontology are as follows
a.]Top level ontology
b;]Domail ontology-Used to describe a given domain[medicine,agriculture]
c.]Task ontology-used for generic asks and activities
d.]Task domail ontologies.]
e.]Application ontology
f.] Method ontology-used to specify a reasoning process so as to achieve a particulr task for linguisticontology
g.] Linguistic ontology- are quite hetrogeneous and are combined with top level and domain-specific ontology to form more coherent resourses
There are mny waysto represent knowledge:
1.]Predicate logic
2.]semantic nets
3.Frames
4.]Sripts
5.]Conceptual graphs
Ontology mark up languages:
There are many ontology mark up languages where shoe is an extension to HTML language which allowed tags to include ontologies.RDF is bases on description logic and RDFS is bases on frames.OIL is also a frame based language,DAML is based on descriptive logic
Application of ontologies;
1.Used for efficient retrieval of information;Information retrieval is aprocess of fetching relevant information from a corpora ,according to queries posed by the users.Most of the IR engine s are thesaurias an vocabulary to enrich user queries and these enriched queries are furher used for fetching relevant documeents from the corpus.Wordnet is afamous lexicon resourse available for being used as an knowledge source to provide useful information
2.It can play important role in IR process;The queries could be more meaningfully enriched which adds to better retrieval effectiveness. Protege,sumo are some of the tools available for builing ontologies.Semantic web is the creation of web of fdata taht can be processed directly /indirectly by machines.Documents of sementic web could possess semantic tags to indetify intra document and interdocument relationship.To make the vision of semantic web true ontology would be used ad one of the major resorces
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