Help:Ontology

Ontologies are used to capture knowledge about some domain of interest. An ontology describes the concepts in the domain and also the relationships that hold between those concepts.

• Components of Ontologies
  • INDIVIDUALS: represent objects in the domain in which we are interested. At the Traditional Tune Archive, the individuals are the traditional tunes.
  • PROPERTIES: are binary relations on individuals - i.e. properties link two individuals together. For example, the property "Has historical geographical allegiances" might link the tune "Craig a' Bhodich" to the tune "Fisher's Hornpipe", or the property "Is also known as" might link the tune "Fisher's Hornpipe" to the tune "Crannciuil Ui Fishuir". Properties can have inverses. For example, the inverse of hasOwner is isOwnedBy. Properties can be limited to having a single value, i.e. to being functional. They can also be either transitive or symmetric.
  • CLASSES: are interpreted as sets that contain individuals. They are described using formal (mathematical) descriptions that state precisely the requirements for membership of the class. For example, the class Tune would contain all the individuals that are tunes in our domain of interest Classes may be organised into a superclass-subclass hierarchy, which is also known as a taxonomy. Subclasses specialise (`are subsumed by') their superclasses. For example consider the classes Music and Tune, Tune might be a subclass of Music (so Music is the superclass of Tune). This says that, `All Tunes are Music', `All members of the class Tune are members of the class Music', `Being a Tune implies that you're a piece of Music', and `Tune is subsumed by Music'.

Ontology Properties:
Properties represent relationships.
There are two main types of properties, Object properties and Datatype properties.
Object properties are relationships between two individuals. Object properties link an individual to an individual.

Object Property Characteristics
Ontology allows the meaning of properties to be enriched through the use of property characteristics.

• Functional Properties
  • If a property is functional, for a given individual, there can be at most one individual that is related to the individual via the property. If we say that the individual "A M Shinnie" Was composed by "Angus Fitchet" and we also say that the individual "A M Shinnie" Was composed by "James Scott Skinner", then because Was composed by is a functional property, we can infer that "Angus Fitchet" and "James Scott Skinner" must be the same individual. It should be noted however, that if "Angus Fitchet" and "James Scott Skinner" were explicitly stated to be two different individuals then the above statements would lead to an inconsistency.

• Inverse Properties
  • Each object property may have a corresponding inverse property. If some property links individual (a) to individual (b) then its inverse property will link individual (b) to individual (a). For example if "A M Shinnie" Was composed by "Angus Fitchet", then because of the inverse property we can infer that "Angus Fitchet" Is the compose of "A M Shinnie". However, at the Traditional Tune Archive, the individuals are the traditional tunes, therefore we haven't linked composers <== and ==> traditional tunes and this property's characteristic wasn't taken into consideration.

• Inverse Functional Properties
  • If a property is inverse functional then it means that the inverse property is functional. For a given individual, there can be at most one individual related to that individual via the property. This is the inverse property of Was composed by since Was composed by is functional, Is the composer of is inverse functional. If we state that "Angus Fitchet" is the Composer of "A M Shinnie", and we also state that "James Scott Skinner" is the composer of "A M Shinnie", then we can infer that "Angus Fitchet" and "James Scott Skinner" are the same individual. However, at the Traditional Tune Archive, the individuals are the traditional tunes, therefore we haven't linked composers <== and ==> traditional tunes and this property's characteristic wasn't taken into in consideration.

• Transitive Properties
  • If a property (P) is transitive, and the property relates individual (a) to individual (b), and also individual (b) to individual (c), then we can infer that individual (a) is related to individual (c) via property (P). For example, if the individual "Jackey Layton" -> Is also known as -> "Jack Lattin", and "Jack Lattin" -> Is also known as -> "Jennie Rock the Craddle", then we can infer that "Jackey Layton" -> Is also known as -> "Jennie Rock the Craddle".

• Symmetric Properties
  • If a property (P) is symmetric, and the property relates individual (a) to individual (b) then individual (b) is also related to individual a via property (P). If the individual "Auld Luckie" is related to the individual "Belfast Linen" via the Appears in property, then we can infer that "Belfast Linen" must also be related to "Auld Luckie" via the Appears in property. In other words, if "Auld Luckie" appears in the Merry Melodies vol. 3 Tune Book, then "Belfast Linen" must appear in the same published issue. Put another way, the property is its own inverse property.

• Asymmetric Properties
  • If a property (P) is asymmetric, and the property relates individual (a) to individual (b) then individual (b) cannot be related to individual (a) via property (P). At the Traditional Tune Archive we don't have any relation of this kind between individuals (tunes)

• Reflexive Properties
  • If a A property (P) is said to be reflexive when the property must relate individual a to itself. At the Traditional Tune Archive we don't have any relation of this kind between individuals (tunes)

• Reflexive Properties
  • If a property P is irrrfexive, it can be described as a property that relates an individual (a) to individual (b), where individual (a) and individual (b) are not the same. At the Traditional Tune Archive we don't have any relation of this kind between individuals (tunes)

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DataType Properties:
They describe relationships between an individual and data values.

A good example could be the DataType Property: Theme Code Index, which is a numerical coding system for identifying initial musical themes, or the DataType Property: In in the key of which we use to state the tone (a finite number) of the traditional tune. Most of the property characteristics described for Object Properties cannot be used with DataType Properties