  We use simulations of isolated galaxies with a few parsec resolution to
explore the connection between the small-scale star formation rate - gas
density relation and the induced large-scale correlation between the star
formation rate surface density and the surface density of the molecular gas
(the Kennicutt-Schmidt relation). We find that, in the simulations, a power-law
small-scale "star formation law" directly translates into an identical
power-law Kennicutt-Schmidt relation. If this conclusion holds in the reality
as well, it implies that the observed approximately linear Kennicutt-Schmidt
relation must reflect the approximately linear small-scale "star formation
law".
