2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/56885The Hofstadter model illustrates the notion of topological quantum numbers and how they account for the quantization of the Hall conductance. It gives rise to colorful fractal diagrams of butterflies where the colors represent the topological quantum numbers.9 pages, 5 figuresMathematical Physicstext