Enumeration of perfect matchings of a type of Cartesian products of graphs (Q2581564)

For a tree \(T\), the authors express the number of perfect matchings in the Cartesian products \(C_4\times T\), \(P_4\times T\) and \(P_3\times T\) (provided \(T\) itself has a perfect matching in this case) in terms of the eigenvalues of the adjacency matrix of \(T\).