In this talk, I will present a characterization for digraphs whose tensor product is weakly connected, which solves an open problem posed by Harary and Trauth (
An L(2, 1)-labeling of a graph is an assignment of nonnegative integers to the vertices of G such that adjacent vertices have numbers at least 2 apart, and vert
It is well-known that each nonnegative integral flow of a directed graph can be decomposed into a sum of nonnegative graph circuit flows, which cannot be furthe
Two q-difference equations with solutions expressed by q-exponential operator identities are investigated.As applications, two extensions of Ramanujans formulas