Ordering of bicyclic signed digraphs by energy

Abstract

Let $\mathcal{S}_n$ be a bicyclic signed digraphs with $n$ vertices whose two signed directed even cycles are vertex-disjoint. In this paper, we characterize the ordering of bicyclic signed digraphs in $\mathcal{S}_n$ by energy with two positive or negative directed even cycles (resp., one positive directed even cycle and one negative directed even cycle). Furthermore, we determine extremal energy in $\mathcal{S}_n$ by the two orderings.