Proof: Let us consider three species A, B and C where A and B belong to a same subclass, contrary to C: species A and B are linked by node N 1 , and species The DD-HDS projection in the two-dimensional output space is computed (code available at http://sy.lespi. free.fr/DD-HDS-homepage.html). A DD-HDS parameter (λ) can be adjusted in order to more or less emphasize smallest distances: 0 (1 respectively) for minimum (maximum respectively) consideration of longer distances. In the following examples, λ is set to 0.5. The output of DD-HDS is the set of coordinates in a 2D space (coordinates