Gregus type fixed points for a tangential multi-valued mappings satisfying contractive conditions of integral type (Q1951829)

The authors generalize the so-called tangential property of four single-valued mappings to that of two single-valued and two multi-valued mappings, supported by a simple example. An existence theorem is proved for a common fixed point of Greguš type of four mappings having this type of generalized tangential property and satisfying a general contractive condition. This theorem is shown to generalize several previously obtained fixed point results.