Non-Archimedean LL-fuzzy normed spaces and stability of functional equations

Lee et al. considered the following quadratic functional equation f(lx+y)+f(lx−y)=2l2f(x)+2f(y)f(lx+y)+f(lx−y)=2l2f(x)+2f(y) and proved the Hyers–Ulam–Rassias stability of the above functional equation in classical Banach spaces.In this paper, we prove the Hyers–Ulam–Rassias stability of the above quadratic functional equation in non-Archimedean LL-fuzzy normed spaces.