The College of Science in the Department of Mathematics discussed a seminar entitled Explicit Forms for Harnack's Inequality for Dirichlet Problem with some Applications of Poisson's Integral Formula and a Study for the Maximum Principle of Harmonic Functions for postgraduate student Sarah Y. Ayoub. The seminar aims to study Poisson's integral formula, giving an explicit form for Harnack's inequality in the open ball, and a study for the maximum principle of harmonic functions.