Coupled coincidence point theorems for mixed monotone nonlinear operators

AbstractWe obtain coupled coincidence and coupled common fixed point theorems for mixed g-monotone nonlinear operators F:X×X→X in partially ordered metric spaces. Our results are generalizations of recent coincidence point theorems due to Lakshmikantham and Ćirić [V. Lakshmikantham, L. Ćirić, Coupled fixed point theorems for nonlinear contractions in partially ordered metric spaces, Nonlinear Anal. 70 (2009) 4341–4349], of coupled fixed point theorems established by Bhaskar and Lakshmikantham [T.G. Bhaskar, V. Lakshmikantham, Fixed point theorems in partially ordered metric spaces and applications, Nonlinear Anal. 65 (7) (2006) 1379–1393] and also include as particular cases several related results in very recent literature

Common fixed points of noncommuting almost contractions in cone metric spaces

In this paper we prove the existence of coincidence points and common fixed points for a large class of almost contractions in cone metric spaces. These results generalize, extend and unify several well-known recent related results in literature