“…Then the necessary and sufficient solvability condition for the Neumann boundary value problem(1.5),(1.6) has the formyjg(y)dy = ∂Ω yj [ψ2(y) − ψ1(y)] dSy, j = 1, 2, ..., nIf a solution exists, then it is unique up to a first order polynomial and can be represented asu(x) = c0 + − s)s −2 v(sx)ds,where cj, j = 0, 1, ..., n, are arbitrary constants, v(x) is the solution of Dirichlet problem (3.1) with the functions g1(x) = r ∂ ∂r + 4 r ∂ ∂r + 3 g(x), ϕ1(x) = ψ1(x), ϕ2(x) = ψ2(x) + 2ψ1(x) and with the additional conditions v(0) = 0, ∂v(0) ∂xj = 0, j = 1, 2, ..., n. In the section two we study properties of some integro-differential operators, which we then use throughout the paper. In section 3 we investigate the Dirichlet problem for biharmonic equation, making use of the explicit form of the Green function found in[9,10,11]. Then in the following section 4, reducing the Neumann problem (1.5),(1.6) to the considered Dirichlet problem, we give the necessary and sufficient solvability conditions for the Neumann problem for the biharmonic equation.…”