Abstract Metric Spaces and Caristi-Nguyen-Type Theorems

Zoran Kadelburg, Stojan Radenović, Suzana Simić

We prove cone metric versions of common fixed point theorems for two and four mappings with the Caristi-Nguyen-type contractive conditions. Also, sufficient conditions for two or four mappings to have no common periodic points are deduced. Examples are given to distinguish these results from the known ones and to show that certain conditions cannot be omitted.