Operation on binary tree
Its hard to say without the knowledge of why a node goes to the left or right of another, and if this carries as a property throughout the tree. If by ambiguously you mean there is more then one valid way of replacing the node and the tree has an ordering structure (such as a binary search tree) then your understanding is correct. The deleted verticie can be replaced with either its in order predecessor, or its in order successor. Both of these will be valid with the ordering property.