2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/161626A new functional model for pairs of commuting isometries is described. Intertwining operators between such models are then studied in order to approach the classification of invariant subspaces of such pairs.31 pagesSpectral TheoryFunctional Analysis47A20, 47A15Bi-isometries and commutant liftingtext