SESZIONE DI TORINO
Modified'' of ``f(R)'' gravity has recently been revived as an alternative to dark energy to explain the present acceleration of the universe. The theory comes in three versions: metric, Palatini, and metric-affine. The successes of, and challenges for, f(R) gravity will be reviewed, with some emphasis on stability issues, the non-viability of the Palatini version, and successful scenarios.

DATA: 30-10-2008