  For the generation of acyclic biological diagrams, from a graph-theoretical
perspective, we introduce the relative diagrams of cyclic permutations with
ramphoid and keratoid vertices of degree 2, which correspond to Motzkin and
Dyck words/paths. The relation between these two types of diagrams, defines the
generation of the first via the permutations of the second, which may be of
assistance in the study and treatment of several biological problems.
