When we have a preorder binary tree with 6 vertices, how can we determine if it's uniquely determined? Preoder means 1 root, two children of the root, left child has two children but right child only has a left child so what does that mean for uniquely determined? Even numbered vertices means one of the children only has one subchild so not everyone has 0 or 2 children.
Assuming the question is related to Ex 3. The question is if there exists a unique binary tree with 6 vertices whose preorder traversal is A B D E C F or can you find two (or even more) different binary trees with 6 vertices that both have A B D E C F as their preorder traversal.
Note that a binary tree is defined as an ordered, rooted tree for which each vertex has at most two children. So, one child is okay.
As defined in the script:
A binary tree is an ordered, rooted tree for which each vertex v has at most two children and, if v has only child, then there is a clear distinction as whether this child is right or left child.
Hence, a vertex can have a right child but no left child.
In a nearly-complete binary tree, this is not possible.
Sv: Re: Uniquely determined binary trees
You could maybe open a new thread in the forum to invite colleagues to discuss this question.