Complex sentence: In probability theory and statistics, the Geometric-Poisson distribution (another different version called the Pólya--Aeppli distribution,) is a combination both of the Geometric distribution and the Poisson distribution, and includes both of them as special cases.
Split into simpler sentences: In probability theory and statistics, the geometric Poisson distribution (also called the Pólya--Aeppli distribution) is a particular case of the compound Poisson distribution. It is a combination of the geometric distribution and the Poisson distribution, and includes both of them as special cases.