Gutlyanskii, V.Y.; Nesmelova, O.V.; Ryazanov, V.I.
(Український математичний вісник, 2017)
Assume that Ω is a domain in the complex plane C and A(z) is 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, 1 ≤ K < ∞. In particular, for semi-linear ...