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Ontology

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Definition of the term "Ontology"

Ontology: in metaphysics, the study of the nature of being and existence, their basic categories and relationships to determine what entities and what types of entities exist [SUMO and Wikipedia]. In computer science, the specification of conceptualization. An ontology contains a taxonomy of classes as well as their properties and instances.

Examples:

 

Definitions and Notations

The notations introduced in this section are offered to make easier the communication between BRs for example through email.

Class

Class: a collection of things sharing some common attribute(s) [Sigma]. Example: “Man”, “Woman” and “Human”.

Property

Property (Slot): a basic or essential attribute shared by all members of a class [Sigma]. Example: “name” and “birthplace” are properties of the class “Human”. Notation: Human[name] means that a “Human” has a property “name”. Inverse property: A “Message” “hasPart” “MessagePart”. A “MessagePart” is “partOf” “Message”. Then “hasPart” and “partOf” are inverse properties.

Cardinality and Type

Cardinality (of a property): the maximum number of elements in a property. Type (of a property): a subdivision of a particular kind of thing [Sigma]; Example: a “Human” has only one birth place but might have several names. The cardinality of the property “birthPlace” is “single” and the one of “name” is “multiple”. “name” and “birthPlace” are of the type “String” and “Place” respectively.

Notation: “String+” means the cardinality of “birthplace” (and “name”) is at least 1. Notation: “String*” means the cardinality of a property can be multiple. Notation: Human[+name =>> String] and Human[+birthplace => Place].

Image:Cardinality.jpg

Instance

Instance: an occurrence of something [Sigma].

Example: Plato is an instance of Man:

Image:Instance.jpg

Notation:

Plato:"Man"

Taxonomy

Taxonomy: a classification of things into classes based on similarities of structure, origin, properties etc [Sigma].

Image:Taxonomy.jpg

Subclass and Superclass

Subclass: a taxonomic category below a class and above an order (superclass is the opposite of subclass). Note: a subclass inherits all properties of its supperclasses. Notation:

Man::Human

means "Man" is a subclass of "Human".

Syntax Conventions

  • Classes and properties are denoted within quotation marks, classes start with a capital letter, properties start with a small letter.

Example: “Human”, “mother”.

  • Concepts denoted with several concatenated terms will be separated by capital letters.

Example: “MailingAddress”, “hasName”.

  • Classes coming from SUMO are denoted as: SUMO:MailingAddress
  • The source of a definition is denoted in square brackets.

Example: [Wikipedia].

Summary of Notations

Image:Notation.jpg

 

SOURCES of Ontology Construction Material

The Ontology modelling is verified by looking into the following sources. The first group of sources is always consulted: