Relative degrees of irreducible morphisms

We answer affirmatively a recently asked question in [5] which relates the degree of an irreducible morphism to the composition of a path of irreducible morphisms between indecomposable modules. We introduce the notion of the degree of an irreducible morphism related to a subcategory D of indA and we study this notion in case D is an element of the postprojective partition {P0,⋯,Pn,⋯,P∞} of indA. We also present a few connections between degrees of irreducible morphisms and the theory of postprojective partition.