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 ...

We consider first-order symmetric system Jy′ −A(t)y = λ∆(t)y with n×n-matrix coefficients defined on an interval [a, b) with the regular endpoint a. It is assumed that the deficiency indices N± of the system satisfies N− ...