Document Type: Research Paper
Beijing Institute of Technology, P. R. China
Changji University, P. R. China
In this paper, a new molecular-structure descriptor, the general sum–connectivity co–index is considered, which generalizes the first Zagreb co–index and the general sum– connectivity index of graph theory. We mainly explore the lower and upper bounds in terms of the order and size for this new invariant. Additionally, the Nordhaus–Gaddum–type result is also represented.