Journal of Inequalities and Applications
Volume 2008 (2008), Article ID 210615, 12 pages
doi:10.1155/2008/210615
Research Article
Stability of a Quadratic Functional Equation in the Spaces of
Generalized Functions
Department of Mathematical Sciences, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, South Korea
Received 30 June 2008; Accepted 20 August 2008
Academic Editor: László Losonczi
Copyright © 2008 Young-Su Lee. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Making use of the pullbacks, we reformulate the following
quadratic functional equation: f(x+y+z)+f(x)+f(y)+f(z)=f(x+y)+f(y+z)+f(z+x)
in the spaces of
generalized functions. Also, using the fundamental solution
of the heat equation, we obtain the general solution and
prove the Hyers-Ulam stability of this equation in the spaces
of generalized functions such as tempered distributions and Fourier hyperfunctions.