The superstability of d'Alembert's functional equation on the Heisenberg group

In this paper, we investigate the superstability of d'Alembert's functional equation f (ab) + f (ai(b)) = 2f (a)f (b), a, b is an element of H, where H is the Heisenberg group and the map i : H -> H is an automorphism of H such that i o i = id (the identity map). (C) 2009 Elsevier Ltd. All rights reserved.