4. The diagram below shows a decision tree for the task of predicting heart disease.33 The descriptive features in this domain describe whether the patient suffers from chest pain (CHEST PAIN) as well as the blood pressure of the patient (BLOOD PRESSURE). The binary target feature is HEART DISEASE. The table beside the diagram lists a pruning set from this domain.

Using the pruning set, apply reduced error pruning to the decision tree. Assume that the algorithm is applied in a bottom-up, left-to-right fashion. For each iteration of the algorithm, indicate the subtrees considered as pruning candidates, explain why the algorithm chooses to prune or leave these subtrees in the tree, and illustrate the tree that results from each iteration.

BLOOD PRESSURE [false] high Vow true false CHEST PAIN [Inc] CHEST BLOOD HEART false \true ID PAIN PRESSURE DISEASE 1 false high false true 2 true low true 3 false low false true high true 5 false high false