“…(i) f (t, ξ), g(t, ξ ) are defined on [a; b] × [A; B] and locally Lipschitz continuous (see[27])with respect to ξ , ξ ∈ [A; B], (A,B, b may be finite or infinite); (ii) g(t, ξ ) f (t, ξ) for any t ∈ [a; b], ξ ∈ [A; B]; (iii) f (t, ξ)is monotone nondecreasing with respect to ξ , ξ ∈ [A; B]. Let us apply the comparison lemma by taking f (t, ξ) = − ξ + ξ 3 ; g(t, ξ ) = −(ω − V (t))ξ + ξ 3 ,…”