Oscillation of difference systems of the neutral type

The authors consider the nonlinear difference systems Δ(xn−anxσ(n))=png(yn)Δ(xn−anxσ(n))=png(yn)Δyn=δqnf(xτ(n)),n∈N(n0) where δ=±1,{an},{pn}δ=±1,{an},{pn} and {qn}{qn} are real sequences, {σ(n)}{σ(n)} and {τ(n)}{τ(n)} are real non-negative sequences of integers, and f,g:R→Rf,g:R→R are continuous with uf(u)>0uf(u)>0 and ug(u)>0ug(u)>0 for u≠0u≠0. The authors obtain sufficient conditions for all solutions of the system to be oscillatory. Examples to illustrate the results are included.