Decision trees question:

Suppose that we have a decision tree with

 Base node | |-----------------| A B |-----| |------| C D E F |--| |--| |--| |--|--| 

Assumptions: Let's assume that A,B,C,D,E, and F are are nodes.

Questions:

• Is the base node basically a question(/division of data in terms of a feature(?)) ?
• Can the questions be repeated? For instance: Does it make sense to talk about A and B or A and E above to be the same question?
• Could someone give me an analogy to look at this? Do the datapoints flow through the tree?
• If (vector X, y) is the input, what would be a good way to look at the Qutput?