... have very important applications in quantum particle physics particularly in connection with both string and E -in nity theory.Bhaskar and Lakshmikantham 4, Lakshmikantham and´Ciri´c 5 ... points in X.SinceFX × X ⊆ gX, we can choosex1,y1∈ X such that gx1Fx0,y0 and gy1Fy0,x0. Continuing in this way we canconstruct two sequences {xn} and {yn} in ... Jeˇsi´c,andJ.S.Ume,“Theexistencetheoremsforfixedandperiodicpointsofnonexpansive mappings in intuitionistic fuzzy metric spaces,” Chaos, Solitons and Fractals, vol. 37,no. 3, pp. 781–791, 2008.12 L.´Ciri´c and V. Lakshmikantham,...