Semantic Nets

• A long standing formal (and frequently implemented) language for knowledge representation is the semantic net.
• It was proposed by Quillian in 1967 as a basis for human semantics.
• Roughly, there is a graph structure.
• Nodes are concepts.
• Arcs are relations that connect nodes.
• Typically, there are a small number of types of relationships.
• A particular important relationship is subcategorisation or IS-A.
• IS-A Hierarchies
• Basis of Object Inheritence
• See my BIS 2040 lecture notes on semantic nets for more.
• Most Knowledge Representation Languages (e.g. KL-One) are based on semantic nets.
• This is really similar to cognitive maps.