In this dissertation, we looked at the cosmological constraints of some f(R)-modi ed gravity models, such as f(R) = Rn (our rst toy model), f(R) = R + Rn (our second toy model), and more realistic ones like the Starobinsky ...

We investigate using dynamical system analysis; the impacts of various interaction models whereby dark energy is coupled with dark matter. Examination on the nature of critical points for each interaction model introduced ...