ID3

Name ID3
Description

The algorithm ID3 (Quinlan) uses the method top-down induction of decision trees.

Given a set of classified examples a decision tree is induced, biased by the information gain measure, which heuristically leads to small trees.

The examples are given in attribute-value representation. The set of possible classes is finite.

Only tests, that split the set of instances of the underlying example languages depending on the value of a single attribute are supported.

Depending on whether the attributes are nominal or numerical, the tests either

  • have a successor for each possible attribute value, or
  • split according to a comparison of an attribute value to a constant, or depending on if an attribute value belongs to a certain interval or not.

The algorithm starts with the complete set of examples, a set of possible tests and the root node as the actual node. As long as the examples propagated to a node do not all belong to the same class and there are tests left,

  • a test with highest information gain is chosen,
  • the corresponding set of successors is created for the actual node,
  • each example is propagated to the successor given by the chosen test,
  • ID3 is called recursively for all successors.

Specialization ID3 Software
Generalization Top-Down Induction of Decision Trees (TDIDT)
Example Languages Attribute-Value
Method Type Algorithm
Measures Information Gain