Oscillation theorems for damped elliptic differential equations of second order. (English) Zbl 1144.35323

Summary: Oscillation theorems for the damped elliptic differential equation of second-order \[ \sum^N_{i,j=1} D_i'a_{ij}(x) D_j y]+ \sum^N_{i=1} b_i(x) D_i y+ c(x, y)= 0 \] are obtained. The results are extensions of averaging techniques due to Coles and Kamenev, and include earlier known results in literature.


35B05 Oscillation, zeros of solutions, mean value theorems, etc. in context of PDEs
35J60 Nonlinear elliptic equations
34C10 Oscillation theory, zeros, disconjugacy and comparison theory for ordinary differential equations