Multilevel coarse grid selection strategy

  We use the Jones-Plassman [8] strategy for finding, in parallel, an independent set in the matrix graph. We are then faced with the choice of letting this independent set function as the coarse or as the fine grid. The former is commonly encountered in Algebraic Multigrid methods [9], the latter is the preferred strategy for multi-colour methods.

For this choice, the user has the following two routines:

int AMLSetCoarseGridDependent(PC pc)
int AMLSetCoarseGridIndependent(PC pc)

It should be noted that choosing the coarse grid as the independent set gives a dramatically lower number of levels than letting it be the dependent set.