  In cosmology, the cosmic curvature $K$ and the cosmological constant
$\Lambda$ are two important parameters, and the values have strong influence on
the behavior of the universe. In the context of normal cosmology, under the
ordinary assumptions of positive mass-energy and initial negative pressure, we
find the initial singularity of the universe is certainly absent and we have
$K=1$. This means total spatial structure of the universe should be a
3-dimensional sphere $S^3$. For the cyclic cosmological model, we have
$\Lambda\lesssim 10^{-24} {\rm ly}^{-2}$. Obviously, such constraints would be
helpful for the researches on the properties of dark matter and dark energy in
cosmology.
