This exercise considers 2 pruning of decision trees. a. Create a data set with two input attributes, such that the information gain at the

This exercise considers χ² pruning of decision trees.

a. Create a data set with two input attributes, such that the information gain at the root of the tree for both attributes is zero, but there is a decision tree of depth 2 that is consistent with all the data. What would χ² pruning do on this data set if applied bottom up? If applied top down?

b. Modify DECISION-TREE-LEARNING to include χ² -pruning. You might wish to consult Quinlan (1986) for details.