2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/117656Some models for the lepton sector, based on seesaw extensions of the Standard Model, are discussed in which the mu-tau interchange symmetry is realized in various ways. The symmetries defining such models and their characteristic predictions for lepton mixing are presented.4 pages, talk presented at ICHEP06, Moscow, July 26 - August 2, 2006High Energy Physics - Phenomenologytext