The authors establish a common fixed point theorem for six selfmaps of a complete metric space satisfying a rational inequality and the condition of either compatibility of G. Jungck
[Int. J. Math. Math. Sci. 9, No. 4, 771-779 (1986; Zbl 0613.54029
)] or weak compatibility of G. Jungck
and B. E. Rhoades
[Indian J. Pure Appl. Math. 29, No. 3, 227-238 (1998; Zbl 0904.54034
)]. Among others, a theorem of A. Ahmad
and of the first author [Publ. Math. 41, No. 3-4, 181-187 (1992; Zbl 0776.54031
)] is generalized.