On some common fixed point theorems with rational expressions on cone metric spaces over a Banach algebra (Q2869492)

Let \((X,d)\) be a complete cone metric space over a Banach algebra, which is a cone metric space in the sense of [\textit{L.-G. Huang} and \textit{X. Zhang}, J. Math. Anal. Appl. 332, No. 2, 1468--1476 (2007; Zbl 1118.54022)], except that the cone metric \(d\) takes values in a Banach algebra. The authors prove some common fixed point results for two, resp.\ four self mappings on \(X\) satisfying certain rational contractive conditions. Also, the \(Q\) property of these mappings is deduced. No examples of such mappings are given.