Abstract In this paper, we study the T -periodic solutions of the parameter-dependent ϕ -Laplacian equation equation* ( (x') ) '=F (, t, x, x'). equation* Based on the topological degree theory, we present some atypical bifurcation results in the sense of Prodi–Ambrosetti, i. e. , bifurcation of T -periodic solutions from λ = 0. Finally, we propose some applications to Liénard-type equations. Dedicated to Professor Maria Patrizia Pera on the occasion of her 70th birthday
Benevieri et al. (Wed,) studied this question.