“…For instance, Theorem 8.3 does not imply the self-adjointness of the combinatorial Laplacian L comb when it is unbounded (see [37], [41,Theorem 6]). However, Theorems 8.1 and 8.3 enjoy a certain stability property under additive perturbations, which preserve semiboundedness ([30, Theorem 2.16], [45]). (iii) We refer for further results and details to [45], [49,Chap.…”