2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/27179A deep connection between the Hall conductance in realistic situation and a topological invariant is pointed out based on von-Neumann lattice representation in which Landau level electrons have minimum spatial extensions. We show that the Hall conductance has no finite size correction in quantum Hall regime, but a coefficient of induced Chern-Simons term in QED$_3$ has a small finite size correction, although both of them are similar topological invariant.13 pages, 2 figures uuencoded, phyzzx, EPHOU-94-005Condensed Mattertext