  In this paper, we study in detail a perfect fluid cosmological model with
time-varying "constants" using dimensional analysis and the symmetry method. We
examine the case of variable "constants" in detail without considering the
perfect fluid model as a limiting case of a model with a causal bulk viscous
fluid as discussed in a recent paper. We obtain some new solutions through the
Lie method and show that when matter creation is considered, these solutions
are physically relevant.
