I am trying to compute the edit distance between two dendrograms, one produced from hierarchical clustering, and the other manually constructed from some tree structure. In this setting, the rename operations on leaves of the tree are not allowed, and renames of other nodes (parent nodes) is free.
The tree edit distance for rooted ordered trees has been well studied, but this problem should be considered for the case where input trees are unordered. For the general case, it is known that tree edit distance problem for unordered trees is NP-hard. However, I don't seem to find an algorithm to find the unordered tree edit distance.
Any pointers or insights into this problem is highly appreciated.