An oscillation criterion for linear difference equations with oscillating coefficients

Relatively few oscillation criteria have been established for delay difference equations of the form yn+1−yn+qnyn−τ=0, where {qn} is an oscillatory sequence. In this note, we make use of the convexity property of the function x ln x to obtain such a criterion which complements some of the existing results even when {qn} is nonnegative.