IsA Relation

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A IsA Relation is a domain independent semantic relation that is a strict partial order relation (antisymmetric, irreflexive, transitive) between a subclass concept and a superclass concept.





  • (Wikipedia, 2009) ⇒
    • In object-oriented programming, inheritance is a way to form new classes (instances of which are called objects) using classes that have already been defined. The inheritance concept was invented in 1967 for Simula. [1]
    • The new classes, known as derived classes, take over (or inherit) attributes and behavior of the pre-existing classes, which are referred to as base classes (or ancestor classes). It is intended to help reuse existing code with little or no modification.
    • Inheritance provides the support for representation by categorization in computer languages. Categorization is a powerful mechanism number of information processing, crucial to human learning by means of generalization (what is known about specific entities is applied to a wider group given a belongs relation can be established) and cognitive economy (less information needs to be stored about each specific entity, only its particularities).
    • Inheritance is also sometimes called generalization, because the is-a relationships represent a hierarchy between classes of objects. For instance, a "fruit" is a generalization of "apple", "orange", "mango" and many others. One can consider fruit to be an abstraction of apple, orange, etc. Conversely, since apples are fruit (i.e., an apple is-a fruit), apples may naturally inherit all the properties common to all fruit, such as being a fleshy container for the seed of a plant.
    • a primitive relation between an object and an idea (an object is subsumed under an idea if that idea represents it, eg Socrates is subsumed under ...
    • A subsumption relation specifies the relative generality of two concepts. A concept A subsumes a concept B if the definitions of A and B logically ...
    • The subsumption relation can be understood as a relation of implication which relates more specific to more general concepts in conceptual taxonomies. In formal terms, subsumption defines a lattice, a kind of partial ordering, which may be represented as a directed acyclic graph. The hierarchical graphs defined by subsumption need not be trees, but can be more general kinds of graph in which child nodes are re-entrant, i.e. a child node may have more than one parent node. However, commonly a subsumption lattice has a core tree structure, with superimposition of more than one tree, or of other cross-classifiying structures. The subsumption relation may be seen as a generalisation relation, in that the subsumer expresses a generalisation over the subsumed.