Restricted independence in displacement function for better estimation of cyclicity - Chen, Xingwu (Sichuan University (Xina). Department of Mathematics) ; Llibre, Jaume (Universitat Autònoma de Barcelona. Departament de Matemàtiques) ; Wang, Zhaoxia (University of Electronic Science and Technology of China. School of Mathematical Sciences) ; Zhang, Weinian (Sichuan University (Xina). Department of Mathematics)