https://uomosul.edu.iq/computerscience/%d8%a7%d9%84%d8%af%d9%88%d8%b1%d8%a9-%d8%a7%d9%84%d8%aa%d8%af%d8%b1%d9%8a%d8%a8%d9%8a%d8%a9-strong-and-weak-convergence/