2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/35069We present a general formalism for studying an inflationary scenario in the two-brane system. We explain the gradient expansion method and obtain the 4-dimensional effective action. Based on this effective action, we give a basic equations for the background homogeneous universe and the cosmological perturbations. As an application, we propose a born-again braneworld scenario.Plenary talk at Gamow Memorial International Conference, Odessa, Ukraine, August 8-14, 2004; 12 pagesGeneral Relativity and Quantum Cosmologytext