Some more interplay of the three Kirchhoffian indices

For any simple connected undirected graph, and the random walk on it, we obtain a formula for the sum of all expected hitting times - normalized by the stationary distribution - expressed in terms of the eigenvalues of a certain modified Laplacian matrix. This allows us to find lower bounds for these sums of hitting times, as well as new lower bounds for the additive degree-Kirchhoff index, in terms of the multiplicative degree-Kirchhoff index and the Kirchhoff index, that improve other bounds found in the literature.