“…A mapping T: A ∪ B ∪ C ⟶ A ∪ B ∪ C is said to be tricyclic provided that T(A) ⊆ B, T(B) ⊆ C, and T(C) ⊆ A, where A, B, and C are nonempty subsets of a metric space (X, d), and a best proximity point of T is a point x ∈ A ∪ B ∪ C such that D(x, Tx, T 2 x) � D(A, B, C) where the mapping D: X × X × X ⟶ [0, +∞) is defined by D(x, y, z): � d(x, y) + d(y, z) + d(z, x) and D (A, B, C): � inf D(x, y, z): x ∈ A, y ∈ B and z ∈ C . Moreover, the mapping T is said to be a tricyclic contraction if it is tricyclic and verifies D(Tx, Ty, Tz) ≤ kD(x, y, z) + (1 − k)δ (A, B, C), for some k ∈ (0, 1) and for all (x, y, z) ∈ A × B × C. For detailed information, we refer to [1,2].…”