Refining the algorithm

• Goal: Find partitions that yield homogeneous sets
  • Requires a metric for homogeneity
• What is the set of possible feature splits?
  • Boolean features:
    • Only one possible split
  • Features with n discrete values:
    • Create a tree with n branches rather than two branches
  • Numerically-valued features:
    • For each concrete value in the training set:
      • Perform a binary split around that value
• From all of the possible splits, we select the split with the highest gain