Semantic network

A semantic network is often used as a form of knowledge representation. It is a directed graph consisting of vertices which represent concepts and edges which represent semantic relations between the concepts.

Semantic networks are a common type of machine-readable dictionaries.

Important semantic relations:

• Meronymy (A is part of B)
• Holonymy[?] (B has A as a part of itself)

• Hyponymy[?] (or Troponymy[?]) (A is subordinate of B; A is kind of B)
• Hyperonymy[?] (A is superordinate of B)

• Synonymy[?] (A denotes the same as B)
• Antonymy[?] (A denotes the opposite of B)

An example of a semantic network is WordNet, a lexical database of English.

The link and lexical structure of the Wikipedia might also be regarded as a simple example of a semantic network, with the following properties:

• article A is linked to article B
• the name of article A is used in the Wikipedia entry for B

Such networks involve fairly loose semantic associations that are nonetheless useful for human browsing. It is possible to represent logical descriptions using semantic networks such as the Existential Graphs[?] of Charles S. Peirce or the related Conceptual Graphs[?] of John F. Sowa. These have expressive power equal to or exceeding standard first-order predicate logic. Unlike WordNet or other lexical or browsing networks, semantic networks using these can be used for reliable automated logical deduction. Some automated reasoners exploit the graph-theoretic features of the networks during processing.

"Semantic Nets" were first invented for computers by Richard H. Richens[?] of the Cambridge Language Research Unit[?] in 1956 as an "interlingua" for machine translation of natural languages. They were developed as "semantic networks" for knowledge representation and reasoning by M. Ross Quillian[?] in 1966.

On can consider a mind map to be a very free form variant of a semantic network. By using colors and pictures the emphasis is on generating a semantic net which evokes human creativity.

See also:

• Semantic Web and this
• Information space

External links:

• WordNet home page (http://www.cogsci.princeton.edu/~wn/)
• [1] (http://www.sigmaxi.org/amsci/issues/comsci99/compsci1999-03) "Computing Science - The Web of Words"