2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/24952Using the topological flux insertion procedure, the ground-state degeneracy of an insulator on a periodic lattice with filling factor $ν=p/q$ was found to be at least $q$-fold. Applying the same argument in a lattice with edges, we show that the degeneracy is modified by the additional edge density $ν_{\mysw{E}}$ associated with the open boundaries. In particular, we demonstrate that these edge corrections may even make an insulator with integer bulk filling degenerate.4 pages, REVTeX 4Strongly Correlated Electronstext