When solving $A*x=b$ using preconditioned conjugate gradient methods one has to solve $z=K^{-1}*r$ for the preconditioning where $K$ is the preconditioner of $A$ and $r$ is the residual vector. Instead of performing classical preconditioning like incomplete Cholesky or ILU one can also perform one V-cycle of algebraic multigrid method(AMG).
Does this mean that the V-cycle is applied to the equation $z=A^{-1}*r$ to get $z$?
I have implemented for first testing a Ruge Stuben based AMG algorithm as a preconditioner for BiCGStab method. But I do not really see improvements in convergency compared to the classical preconditioners.