2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/57334Topological quantum numbers account for the precise quantization that occurs in the integer Hall effect. In this theory, Kubo's formula for the conductance acquires a topological interpretation in terms of Chern numbers and their non-commutative analog, the Fredholm Indices.Mathematical Physicstext