Estrada Index of Signed Spongy Hypercube Constructed on Octahedron Graph

Let G be an n−vertex graph and λ1³ λ2³ … ³λn be the eigenvalues of the adjacency matrix of G in non-increasing ordering. The Estrada index of G, EE(G), is defined asthe sum of all ex, where x runs on the multi-set of all eigenvalues of G. For a general graph, this number can be obtained as the sum of the subgraph centralities of all nodes in the graph. A signed graph consists of a simple graph togetherwith a function􀟪􀇣􀀃􀜧 􀕜 􁈼􀵅􀇡 􀵆􁈽 which is called its signature. The Cartesian product of a signed graph and Qkis called a signed spongy hypercube.In this talk, the Estrada index of signed spongy hypercube O □ Qkis computed, where O is an octahedron graph.