The $\Omega_{DE}-\Omega_{M}$ Plane in Dark Energy Cosmology
  The dark energy cosmology with the equation of state $w=constant$ is considered in this paper. The $\Omega_{DE}-\Omega_{M}$ plane has been used to study the present state and expansion history of the universe. Through the mathematical analysis, we give the theoretical constraint of cosmological parameters. Together with some observations such as the transition redshift from deceleration to acceleration, more precise constraint on cosmological parameters can be acquired. 
Yuan Qiang, Tong-Jie Zhang (Department of Astronomy, Beijing Normal   University)