In this work, we give conditions for the superposition of independent point
processes to converge to a nonhomogeneous two-dimensional Poisson process.
Using our results, not only that of Grige-lionis (1963) and Weissman (1975
), but also some limiting results related to thinned point processes can be
obtained. Hence this establishes the connection between thinnings and supe
rpositions of point processes.