As we saw in this question, the recommended strategy of building a decision tree is postpruning.
The two methods for that are subtree replacement and subtree raising. At each node, an algorithm decides whether it should perform subtree replacement, subtree raising, or leave the subtree as is.
- Subtree replacement selects a subtree and replaces it with a single leaf.
- Subtree raising selects a subtree and replaces it with the child one (ie, a "sub-subtree" replaces its parent)
What are the pros and cons, when should we use each?