Three sphere inequality for second order elliptic equations with coefficients with jump discontinuity (Q1627688)

In this short note the authors refine the geometry of the three-region inequalities obtained by \textit{E. Francini} et al. [J. Differential Equations 261, No. 10, 5306--5323 (2016; Zbl 1356.35103)] and get a three-sphere inequality for second order elliptic equations with Lipschitz coefficients which jump at a given \(C^{1,1}\) hypersurface.