Karapınar, ErdalKhojasteh,F.Karapinar,E.Khandani,H.Mathematics2024-07-052024-07-052016121687-182010.1186/s13663-016-0501-z2-s2.0-85007524192https://doi.org/10.1186/s13663-016-0501-zhttps://hdl.handle.net/20.500.14411/3802In this work, partial answers to Reich, Mizoguchi and Takahashi’s and Amini-Harandi’s conjectures are presented via a light version of Caristi’s fixed point theorem. Moreover, we introduce the idea that many of known fixed point theorems can easily be derived from the Caristi theorem. Finally, the existence of bounded solutions of a functional equation is studied. © 2016 Khojasteh et al.eninfo:eu-repo/semantics/openAccessBoyd and Wong’s contractionCaristi’s fixed point theoremHausdorff metricMizoguchi-TakahashiReich’s problemArticleQ320161