On maximum Estrada indices of bipartite graphs with some given parameters

The Estrada index of a graph G is defined as EE(G)=∑i=1neλi, where λ1, λ2,…,λn are the eigenvalues of the adjacency matrix of G. In this paper, we characterize the unique bipartite graph with maximum Estrada index among bipartite graphs with given matching number and given vertex-connectivity, edge-connectivity, respectively.