Essential spectrum of elliptic systems of pseudo-differential operators on $L^2({\mathbb{R}}^N)\oplus L^2({\mathbb{R}}^N)$

Orif O. Ibrogimov, Christiane Tretter

Inspired by a result of Wong (Commun. Partial Differ. Equ. 13(10):1209-1221, 1988), we establish an analytic description of the essential spectrum of non-self-adjoint mixed-order s…