Biset, Tesfa (PhD)Debebe, Wubshet2019-11-252023-11-042019-11-252023-11-042019-07-05http://etd.aau.edu.et/handle/123456789/20252This paper is concerned with harmonic function and partial di erential equation. Harmonic functions are regarded as solutions of Laplace equation which have a number of properties that are essential in solving partial di erential equation.Poisson integral is applied to obtain useful inequalities for positive harmonic functions.enHarmonic FunctionPartial DiErential EquationsThesis