Semantic Nets

• In a semantic net, nodes represent concepts (or classes), instances, and values.
• The important ones are the classes.
• So dog (a class) is represented as a node. So is collie.
• Lassie is an instance and is also represented by a node.
• 4-legs is a value, and is also typically represented by a node.
• Relations are represented by arcs.
• So, there is an arc between collie and dog.
• It's directional.
• Semantic nets have a restricted set of arcs, though it's up to the developer to define the set.
• In this case, the arc is an IS-A. This corresponds to subclassing in, e.g., Java.
• Collie and Lassie are also connected by an arc, but its type is Instance-Of. This corresponds to instantiating a class in, e.g., Java.