into the 2:3 MMR, and then the evolution is the same as in the previous simulation. Thus, the migration reversal found in MS01 does not depend on the history of the previous migration. For this reason, and because of the arguments described above in favor of a close formation of Saturn, in the following simulations we will always release Saturn at a distance of 1.4 (which corresponds to the typical position of the edge of Jupiter’s gap).

Dynamics of Jupiter and Saturn as a function of the disk properties and simulation parameters {#dependences}
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To explore how the dynamics of Jupiter and Saturn is affected by the main parameters of the problem, we use, from now on, the numerical scheme described in Crida et al. (2007). In this scheme, the disk is represented using a system of 2D and 1D grids. The main portion of the disk, in which the planets evolve, is represented with a 2D grid in polar coordinates, as usual. The origin of the coordinates is the barycentre of the system. The inner part of the disk (ranging from the inner physical radius, e.g. the X-wind truncation radius at a few tenths of AU, to the inner 