An antimaximum principle for periodic solutions of a forced oscillator Albouy, Alain Ureña Alcázar, Antonio Jesús Antimaximum principle Forced linear oscillator Positive solutions Separation of convex sets Consider the equation of the linear oscillator u '' + u = h(theta), where the forcing term h : R -> R is 2 pi-periodic and positive. We show that the existence of a periodic solution implies the existence of a positive solution. To this aim we establish connections between this problem and some separation questions of convex analysis. 2022-09-28T11:35:54Z 2022-09-28T11:35:54Z 2022-01-23 journal article Published version: Albouy, A. & Ureña, A. J. An antimaximum principle for periodic solutions of a forced oscillator. Communications in Contemporary Mathematics (2022) 2250041. [https://doi.org/10.1142/S0219199722500419] https://hdl.handle.net/10481/77053 eng http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional World Scientific