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math.FA2021
Best proximity points in ultrametric spaces
Karim Chaira, Samih Lazaiz
In the present paper, we study the existence of best proximity pair in ultrametric spaces. We show, under suitable assumptions, that the proximinal pair has a best proximit…
math.FA2020
On Caristi fixed point theorem for set-valued mappings
Karim Chaira, Soumia Chaira, Samih Lazaiz
The aim of this paper is to discuss Penot's problem on a generalization of Caristi's fixed point theorem. We settle this problem in the negative and we present some new theorems on…