Gregus-type common fixed point theorems for tangential multivalued mappings of integral type in metric spaces (Q539411)

Summary: The concept of tangential for single-valued mappings is extended to multivalued mappings and used to prove the existence of a common fixed point theorem of Gregus type for four mappings satisfying a strict general contractive condition of integral type. Consequently, several known fixed point results are generalized and improved as the corresponding recent results of \textit{H. K. Pathak} and \textit{N. Shahzad} [Bull. Belg. Math. Soc. - Simon Stevin 16, No.~2, 277--288 (2009; Zbl 1167.54016)] and many authors.