2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/186313We study the geometry of the phase space of spatially flat Friedmann-Lemaitre-Robertson-Walker models in f(R) gravity, for a general form of the function f(R). The equilibrium points (de Sitter spaces) and their stability are discussed, and a comparison is made with the phase space of the equivalent scalar-tensor theory. New effective Lagrangians and Hamiltonians are also presented.14 pages, 2 figures, published in Classical and Quantum Gravity; references addedGeneral Relativity and Quantum CosmologyAstrophysicsHigh Energy Physics - Theorytext