A linear differential equation with advanced-argument
y′(t)−c(t)y(t+τ)=0 is considered where
c:[t0,∞)→[0,∞),
t0∈R is a bounded and locally Lipschitz continuous function and
τ>0. The well-known explicit integral criterion
guarantees the existence of a positive solution on
[t0,∞). The paper derives new integral criteria involving the coefficient
c. Their independence of the previous result is discussed as well.