Let πββ and Ξ be a quiver with adjacency matrixπ΄(Ξ)=(πππ)ππ,π=1.
A π-weight is a positive integral π-eigenvector of π΄, graph
i.e. π£πββ such that
πβπ=1ππππ£π=ππ£π
A quiver is called π-weightable iff a π-weight exists.1