Gutlyanskii, V.Ya.; Nesmelova, O.V.; Ryazanov, V.I.
(Доповіді НАН України, 2018)
We study semilinear elliptic equations of the form div(A(z)∇u) = f(u) in Ω⊂ C, where A(z) stands for a symmetric 2×2 matrix function with measurable entries, det A =1, and such that 1/ K |ξ|² ≤ 〈A(z)ξ,ξ〉 ≤ K |ξ|², ξ ∈ R², ...