}
\details{
Two methods are available: the one by Penny and Hendy (1985), and the
- branch length score by Kuhner and Felsenstein (1994).
+ branch length score by Kuhner and Felsenstein (1994). The trees are
+ always considered as unrooted.
The topological distance is defined as twice the number of internal
branches defining different bipartitions of the tips (Penny and Hendy