why for a is it $2^$h$-1-1$ and not n$-1.$ n being the nb of nodes? Say we have our worst case full binary tree where the root has $2$ children, the right child is a leaf and the left one again has $2$ children, the right one there is also a leaf, and the left has $2$ children that are both leaves. in this case, let v be a node in the tree. for each internal node, the left subtree contains all the leaves and the rught subtree has none, or is just a leaf. If the imbalance$($v$)$ is abs$($left subtree $-$ right$),$ would it not be $($n$-1)-0$ as there are $0$ nodes on the right? so the upper bound would be n$-1?$